Original A rticle A Modified Cord Blood Collection Method Achieves Sufficient Cell Levels for Transplantation in Most Adult Patients Rafael Bornstein,a,b Ana I. Flores,a M. Angeles Montalbán,b Manuel J. del Rey,c Javier de la Serna,b Florinda Gilsanz a,b a
Madrid Cord Blood Bank, bDepartment of Hematology, cDepartment of Immunology, Hospital Universitario 12 de Octubre, Madrid, Spain Key Words. Antigens • CD34 • Cord blood banks • Cord blood stem cell transplantation Hematopoietic stem cells • Placental circulation
Abstract Umbilical cord blood transplantation (UCBT) has been used increasingly in both pediatric and adult patients. The total nucleated cell (NC) dose infused is the most critical factor in determining speed of engraftment and survival. Using standard collection techniques, the mean NC content of UCB units is about 10 × 10 8, and only 25% of these units reach the target cell dose of 2 × 107/kg in UCBT patients weighing 50–70 kg. We have designed a modified placental/umbilical two-step collection method in which a standard blood fraction obtained by umbilical venipuncture is combined with a second fraction harvested after placental perfusion with 50 ml heparinized 0.9% saline. This second fraction contributed 32% volume and 15% NCs to the whole UCB unit (123.7 ± 50.1 ml and 1.26 ± 0.52 × 109 NC). The proportion of progenitor cells
in both fractions was not significantly different, indicating that the hematopoietic potential of these larger units is 20% (range, 2%–100%) higher than UCB units collected by standard methods. In addition, the bacterial contamination rate associated with this novel collection method (2.78%) compares favorably. Since 1998 we have further enriched our units by processing only UCB units over 0.8 × 109 NCs, resulting in a 36% cell increment (1.46 ± 0.52 × 10 9 NCs). Thus, 84% and 54% of the Madrid UCB Bank inventory would fulfill the target cell dose of 2 × 107/kg in patients weighing 50 and 65 kg, respectively. This significant UCB banking improvement gives larger pediatric and adult patients a greater chance of finding adequate grafts in order to achieve better clinical outcomes after UCBT. Stem Cells 2005;23:324–334
Introduction
de.netcord.org/index.html]. The data published so far indicate
In the last decade, hematopoietic cell transplantation (HCT)
that UCB is a viable alternative source of hematopoietic stem
using umbilical cord blood (UCB) grafts has increas-
cells (HSCs), and in certain situations may have advantages
ingly been used, particularly for pediatric but also for adult
over unrelated donor marrow grafts [1–5, 8, 10].
patients [1–11]. As reported by NetCord, more than 2,500
Based on this extensive experience in UCBT, the total
unrelated umbilical cord blood transplants (UCBTs) have
nucleated cell (NC) dose infused has emerged as the most
been performed, one-third in adult recipients [https://office.
critical factor in determining speed of engraftment and
Correspondence: Rafael Bornstein M.D., Ph.D., Madrid Cord Blood Bank, Hospital 12 de Octubre, Avda. de Córdoba, s/n, Madrid 28041, Spain. Telephone: 34-91-390-8419; Fax: 34-91-390-8483; e-mail:
[email protected] Received March 2, 2004; accepted for publication November 9, 2004. ©AlphaMed Press 1066-5099/2005/$12.00/0 doi: 10.1634/stemcells.2004-0047
Stem Cells 2005;23:324–334 www.StemCells.com
Bornstein, Flores, Montalbán et al. survival after UCBT [3, 4, 6, 7, 10, 11]. Among 0–2 antigen HLA-mismatched grafts, current data suggests for the same cell dose, survival is superior with better-matched grafts. Although, the negative effect of HLA-mismatch can be at least partially overcome by a higher cell dose [10, 12]. Therefore, the fixed cell content of a UCB unit represents the major limiting factor, particularly for adult recipients. However, the patient’s age does not appear to affect the UCBT outcomes, provided the cell dose is adequate [13]; a conception supported by the most recent UCBT series in adult patients in which engraftment and survival rates were comparable to those seen in child recipients [14–16]. Several reports have suggested that a threshold number of nucleated cells is needed for engraftment. Particularly poor results are seen after UCBT in both children and adults when the NC dose infused is less than 1.5 × 107/kg [17–19]. Above this figure, there is a level—the “optimal” dose—which is associated with a distinct survival advantage. Gluckman et al. [3] have shown that a graft NC dose > 3.7 × 107/kg was associated with shorter time to neutrophil recovery (25 versus 34 days) and higher engraftment rate (94% versus 76%). While both the minimum acceptable and the optimal UCB graft cell doses are yet to be unanimously agreed upon, most of the available data suggests there is a threshold effect somewhere within this range and that a target (advisable) cell dose must be between 1.5 and 2.5 × 107/kg. Many transplant centers would now recommend 2 × 107/kg as a reasonable target cell dose to obtain satisfactory UCBT outcomes [8, 14, 17, 20–22]. As the finite number of HSCs in single UCB units may result in underutilization of this alternate stem cell source in larger pediatric and adult recipients, UCB banks should focus on the collection of larger units with greater numbers of cells [23]. Using the standard collection technique, the mean number of NCs reported by the biggest UCB banks worldwide is about 10 × 108 per unit [24–26], and with this cell content, only 25% of UCB units contain enough cells to fulfill the target dose for transplantation in patients weighing 50–70 kg [27]. Here we present data on the increase in UCB cell retrieval by using a modified placental/umbilical collection method. By means of these enriched UCB units, a cell dose of 2 × 10 7/kg would be achieved in most larger pediatric patients and in a significant proportion of heavier adult patients requiring HCT.
Materials and Methods “Two-Fraction” UCB Collection Umbilical cord blood was obtained from healthy term newborns after vaginal delivery at Hospital 12 de Octubre. A consent form approved by the Institutional Review Board
325 was signed by all mothers whose medical and family history obtained prior to collection did not reveal any exclusion criteria for UCB donation. The blood was obtained using a two-fraction collection protocol. The first blood fraction was obtained with the placenta in utero, according to the procedure used in most of the UCB banks. Briefly, the cord was double clamped, transected, and cleaned with iodine and alcohol. A 16-gauge needle from the collection bag was inserted into the umbilical vein; blood was allowed to flow by gravity until the blood flow ceased (Fig. 1A). The second blood fraction was collected from the delivered placenta by flushing the placental vessels with 50 ml of 0.9% saline (Baxter Healthcare, Round Lake, IL; http://www.baxter.com) plus 5,000 units of preservative-free heparin (Rovi, Madrid, Spain; http://www. rovi.es). The placenta was placed over a sterile cloth, and the vessels around the cord insertion were cleaned as above. Two large-size vessels were cannulated, trying to select an artery and a vein whenever they could be distinguished, for the saline infusion and the blood collection, respectively (Fig. 1B). The saline bag was hung on a dripstand to allow the saline solution to enter the placental circulation, and the blood was recovered into the collection bag. The “umbilical venipuncture” and “placental perfusion” fractions are named the “first” and “second” UCB fractions, respectively.
Figure 1. Umbilical cord blood collection by a “two-fraction” harvest procedure. First and second blood fractions were obtained by (A) umbilical venipuncture and (B) placental perfusion. Both fractions were collected (C) into separate standard blood donor bags and then pooled prior to processing or (D) directly into a single Stemflex bag. Units from groups I and II were collected using the standard blood donor bags (C), and units from group III were collected into Stemflex bags (D).
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The Madrid Cord Blood Bank came into operation in 1996. From 1996 to 2003, standard blood donor bags (Grifols, Barcelona, Spain; http://www.grifols.com) containing 63 ml citrate phosphate dextrose (CPD) anticoagulant with adenine were used for the collection of UCB units (groups I and II, see below). The original volume of CPD-adenine was reduced to 23 ml. Two separate bags were used for the collection of the first (Fig. 1A) and second blood fractions (Fig. 1B), and the two fractions were pooled in a transfer bag (Fig. 1C). After July 2003 the first and second UCB fractions were collected using a single bag (Stemflex, Maco Pharma, Tourcoing, France; http://www.macopharma. com) with two collection lines for the retrieval of each blood fraction into the same container (group III, Fig. 1D). These Sternflex bags contain 21 ml CPD. To recover all the blood, the collection lines were washed with 8 ml CPD from a satellite bag, making the total amount of anticoagulant in the collection bag 29 ml. From 1996 to 1998, units containing 0.4 × 109 or more NCs were processed within 48 hours of collection (group I: 351 units). Since 1998 UCB processing was restricted to units over 0.8 × 109 NCs (group II: 1,269 units; group III: 319 units).
UCB Processing and Sampling The UCB volume was estimated by subtracting the tare weight of the bag and the volume of anticoagulant from the total weight of the blood-containing bag, assuming that 1 g of blood is equivalent to 1 ml. To count the total number of nucleated and progenitor cells, 2 ml of sample were removed from the blood-containing bags. Nucleated cell count was assessed with an automated hematology analyzer (AC•T diff; Coulter, Miami, Florida, http://www.beckman.com), and the total number of cells was calculated by multiplication with the blood volume contained in the bag. The UCB was processed with hydroxyethyl starch, as described [28]. Bacterial contamination in the entire unit was determined on the sedimented red blood cells. Samples were removed for aerobic and anaerobic bacterial cultures in BacT/ Alert media (Biomérieux, Durham, NC; http://www. biomerieux.com). To determine the contribution of the second UCB fraction to the total volume and number of NCs, the first and second fractions of 44 units from group I were analyzed separately. Also, hematopoietic progenitor cells (HPCs) were assessed on each blood fraction from an additional subset of 10 units from group I (see below).
Hematopoietic Progenitor Cell (HPC) Assays CD34+ cell enumeration was performed by flow cytometry using the ISHAGE gating strategy [29]. Cells were incubated with CD34 phycoerythrin (PE) and CD45 fluorescein isothiocyanate (FITC) antibodies (Becton, Dickinson, Erembo-
Increased UCB Retrieval by Placental Perfusion degem, Belgium; http://www.bd.com) for 20 minutes. After washing, stained cells were analyzed on a FACSort flow cytometer using the CellQuest version 3.3 software (both from Becton, Dickinson). The expression of CD133 was assessed by a three-color assay with CD45 peridinin-chlorophyll-protein complex (PerCP), CD34 FITC, and CD133 PE (Myltenyi Biotec, Bergisch Gladbach, Germany; http://www.miltenyi biotec.com). Prior to data acquisition, a CD34+/CD45dim gate was established for the analysis of CD133+ cells. A minimum of 500 events was acquired in list mode. Colony-forming cells [colony-forming units granulocytemacrophage (CFU-GM), blast-forming units erythrocyte (BFU-E)] were determined in 24-well culture dishes (Nunc, Roskilde, Denmark; http://www.nuncbrand.com). Cells at a density of 50,000/ml were cultured in a medium containing 30% fetal bovine serum, 1% bovine serum albumin, 10 –4 M 2-mercaptoethanol, 2 mM L-glutamine, 10% agar leukocyte conditioned medium, 3 U/ml erythropoietin, and 0.9% methyl cellulose in Iscove’s modified Dulbecco’s medium (IMDM; Methocult H4431, StemCell Technologies, Vancouver, BC, Canada; http://www.stemcell.com). Triplicate 0.3-ml cultures were incubated at 37°C in 100% humidified 5% CO2 in air for 14 days prior to scoring as CFU-GM and BFU-E colonies.
Detection of Maternal DNA in UCB Samples Collected by the Two-Fraction Method The level of cord blood contamination by maternal cells was determined by locus-specific amplification of noninherited maternal HLA-DRB1 genes using the HLA Micro SSP kit (One Lambda, Canoga Park, CA; http://www.onelambda. com). Twenty UCB units from group II were selected for the analysis. Briefly, genomic DNA from cord and maternal blood samples was isolated by a DNA purification system (Gentra, Minneapolis, MN; http://www.gentra.com), and the DRB1 alleles were determined by Reverse Dot Blot (INNO-LiPA; Innogenetics, Gent, Belgium; http://www.innogenetics.com). Sequence-specific primer-polymerase chain reaction (PCR) amplification of the noninherited maternal DRB1 allele was performed on cord blood samples as recommended by the manufacturer. A pair of β-globin primers was used as loading control. The PCR products were run on 2% agarose gels and stained with ethidium bromide (0.5 μg/ml). The sensitivity of the Micro SSP technique was performed by diluting DRB1*04+ and DRB1*07+ blood samples into a negative blood sample at different proportions. Mononucleated cells from positive samples were diluted at 10%, 5%, 2%, 1%, and 0.5%; genomic DNA was then extracted, and DRB1*04 or DRB1*07 genes were amplified. Specific bands were clearly visible in all samples except for the 0.5% dilution. Thus, the limit of sensitivity of the DRB1 detection using SSPPCR and electrophoresis gels was 1% (data not shown).
Bornstein, Flores, Montalbán et al.
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Statistical Analysis For the comparative analysis of volume, NC and HPC content in first and second UCB fractions, the paired-samples T test was used. Similar comparisons between different units were done with the nonparametric Mann-Whitney U test. The Pearson’s correlation coefficient was used to estimate a correlation between volume and NCs and between NCs and CD34+ cell content. A two-sided p < .05 was considered to be significant. Calculations were performed with SPSS 7.5 for Windows (SPSS Inc, Chicago, IL) statistical software package.
Results Increase in UCB Cell Retrieval by Using a Modified Placental/Umbilical Collection Method The technique for UCB collection used in this study comprises two separate blood harvestings. We hypothesized that a second blood fraction obtained after placental perfusion in addition to the standard umbilical venipuncture collection would result in higher blood volume and NC yield. Indeed, we observed a significant correlation between UCB volume and cell content (Fig. 2). By using this novel technique we obtained an average volume of 119.6 ml (range, 27–279 ml) and a NC content of 1.21 ± 0.52 × 109 (group I, Table 1). As
compared to data reported by other banks [24–26, 30–35], where the average volume of UCB units is 71–98 ml and the cell content ranges from 0.85 to 1.05 × 109, our results suggest that the additional blood collected after placental perfusion may increase the total number of NCs. To determine more precisely the benefits of collecting a second fraction, we analyzed the contribution of both UCB fractions in 44 units from group I (Table 2). Although the umbilical venipuncture fraction provided most of the total volume and NC content, the second fraction contribution was 32% and 15%, respectively. However, the NC number provided by the second fraction was very variable between units (Fig. 3). In approximately one out of four (27%) units the second fraction had a contribution of more than 20% of the total cell content, whereas in one out of three (34%) units the cell profit was minimal ( 1 × 10 9 or > 1.3 × 10 9 NCs NCs ≥ 1 × 10 9
NCs ≥ 1.3 × 10 9
Venipuncture
50
30
Venipuncture + placental
70
41
UCB collection fraction
perfusion The data show the percentage of UCB units (n = 44) in which the NCs in the first fraction (venipuncture) and in the whole UCB unit once the first and second fractions were pooled (venipuncture + placental perfusion) are equal to or higher than 1 × 10 9 and 1.3 × 10 9, respectively. Abbreviations: NC, nucleated cell; UCB, umbilical cord blood.
Bornstein, Flores, Montalbán et al.
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No Increase in Risk of Maternal Cell Contamination with the Placental Perfusion Fraction We used locus-specific amplification of the noninherited maternal DRB1 genes to determine the presence of maternal cells in UCB units collected by the two-fraction method. DNA samples from 20 units from group II were amplified with DRB1-specific and β-globin (control) primers. The noninherited maternal genes analyzed were DRB1*07 (in five units), *04 (three units), *11 (three units), *14 (two units), *15 (two units), and *01, *08, *12, *13, and *17 (one unit each). The sensitivity of the technique was 1% (see Materials and Methods). Two representative cases are shown in Figure 6. Whereas cord blood DRB1–specific genes were amplified, we did not
Figure 4. Comparative analysis of CD34 + /CD133 + cells content in first and second UCB fractions. The data show CD34 + or CD133 + (or both) cell counts (mean ± SD) in the first and second UCB fractions. The proportion of CD34 + cells in the fraction harvested by umbilical venipuncture (fraction 1) and in the fraction obtained after placental perfusion (fraction 2) was 0.36% ± 0.18% and 0.33% ± 0.2%, respectively. CD34 + /CD133+ cells were 0.32% ± 0.17% and 0.33% ± 0.19%, whereas CD34 + /CD133– cells were lower than 0.03% in both fractions. CD34 – /CD133 + were barely detectable. Differences between both UCB fractions are not significant (paired-samples T test, n = 10). Abbreviation: UCB, umbilical cord blood.
detect PCR products for the noninherited maternal DRB1 alleles. Therefore, no maternal DNA could be detected in any of the UCB units tested, indicating that the second fraction seems not to increase the level of cord blood contamination by maternal cells reported by other groups [38, 39].
Use of Specific UCB Collection Bags To simplify the harvesting procedure, we recently introduced a specific bag for UCB collection (Stemflex, Maco Pharma) with two lines for the retrieval of each blood fraction into the same container (Fig. 1D). This new bag allows us to proceed with the protocol without substantial modifications. The volume of blood collected into these bags (group III, n = 319) was 118.9 ± 39 ml,
Figure 5. Comparative analysis of CFU-GM and BFU-E (mean ± SD) in first and second umbilical cord blood (UCB) fractions. The number of CFU-GM in the fraction harvested by umbilical venipuncture (fraction 1) and in the fraction obtained after placental perfusion (fraction 2) was 39.56 ± 17.76 × 104 and 10.54 ± 8.28 × 104, respectively, whereas BFU-E numbers in each of these fractions were 83.77 ± 28.88 × 104 and 15.22 ± 9.98× 104 (n = 10). The CFU-GM and BFU-E absolute numbers in the first and the second fractions are proportional to the total number of nucleated cells (see Table 2). Abbreviations: CFU-GM, colony forming units–granulocyte macrophage.
Table 4. NC content in UCB units stored prior to or since the use of the 0.8 × 10 9 NC processing restriction No. of units (%) NC (× 10 9 )
≥ 1.0 × 10 9 NCs
≥ 1.3 ×10 9 NCs
Units pnr (group I)
1.21 ± 0.51*
219 (62)
140 (40)
Units pr (group II)
1.46 ± 0.52*
1066 (84)
692 (54)
Results (mean ± SD) show the NCs of the first 351 UCB units (group I) processed before setting the cell size restriction at 0.8 × 10 9 NCs for UCB unit acceptance into the bank (pnr = processing not restricted), and the same parameters in the following 1,269 UCB units (group II) processed when the 0.8 × 10 9 NC threshold was already operative (pr = processing restricted). Columns two and three show the number (percentage in parentheses) of UCB units with an NC content equal to or higher than the indicated values. *Significantly different (p < .001, Mann-Whitney U test). Abbreviations: NC, nucleated cell; UCB, umbilical cord blood.
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and the NC content was 1.46 ± 0.58 × 109 NC. These data are similar to the results obtained with the standard blood donor bags (Table 4). Bacterial contamination in the new bags was 2.19%, a rate slightly lower than the one observed with the standard bags.
Discussion Many reports have documented the feasibility and efficacy of mismatched unrelated UCBT in pediatric patients [3, 6, 7, 11, 36, 40]. Since unrelated donor bone marrow transplantation in adults is associated with a high risk of graftversus-host disease (GVHD) and treatment failure [41–44], UCBT may also have an advantage in adult recipients due to potentially decreased risk of GVHD. There have been more than 1,000 transplants done in adults, with long-term disease-free survival particularly seen in younger patients with earlier stages of disease [8, 14–16, 20, 22]. However, as cell dose is associated with survival, this considerably limits the pool of eligible UCB grafts for adult patients. Sev-
Figure 6. PCR amplification with sequence-specific primers for the noninherited maternal DRB1 allele. Two representative analyses are shown. (A): Cord blood and maternal DRB1 genes were *04, *07 and *07, *12, respectively. Lane 1: molecular size marker (123-bp ladder); lane 2: negative control (no DNA); lanes 3 and 4: amplifications using primers for DRB1*12 (noninherited maternal gene); lanes 5 and 6: amplifications using primers for DRB1*04 (UCB-specific gene). (B): Cord blood and maternal DRB1 genes were *10, *15 and *07, *10, respectively. Lane 1: molecular size marker; lane 2: amplification using primers for DRB1*10 (maternal and UCB genes); lanes 3 to 9: amplifications using primers for DRB1*07 (noninherited maternal gene); lane 10: negative control (no DNA). Cord blood DRB1*04 (A) and DRB1*10 (B) products were detected (arrows), whereas the noninherited maternal DRB1 alleles were not amplified. β-globin amplification was used as a loading control (arrowheads). Abbreviations: PCR, polymerase chain reaction; UCB, umbilical cord blood.
Increased UCB Retrieval by Placental Perfusion eral strategies to increase the nucleated/CD34 + cell dose are being investigated, including ex vivo expansion of UCB hematopoietic cells [45–47] and multiunit UCB transplant [48]. There are other potential approaches, such as UCBT combined with infusion of mesenchymal stem cells or haploidentical HSCs [49] and UCBT after a nonmyeloablative preparative regimen [50, 51]. Although initial results are encouraging, further studies are required to show a clinical benefit associated with any of these approaches. In the meantime, the importance of cell dose for transplantation outcomes provides the most compelling argument for focusing on the collection of UCB grafts with greater number of cells than units obtained by current protocols. Based on the harvest technique proposed by Turner et al. [52], we designed a two-phase collection method in which a blood fraction obtained by umbilical venipuncture, similar to the procedure used in most banks, is followed immediately upon placental delivery by a 0.9% saline perfusion. This method allows retrieving additional blood from placental vessels, which results in an increase in the total number of NCs with no extra risk of bacterial contamination. Because the two-fraction collection method provides more NCs per unit, we also introduced a processing restriction that should
Figure 7. Increase in the nucleated cell content in the umbilical cord blood (UCB) units stored at the Madrid UCB Bank due to the “two-fraction” collection method and the processing restriction to units with a nucleated cell (NC) count ≥ 0.8 × 10 9. For this comparison the cell content of the first fraction was considered as 100% (V [pnr]; n = 44). The second fraction collection produces a 13% increase in the total number of NCs (V + PP [pnr]; n = 351). Besides the second fraction, the restriction in the processing of units with an NC count ≥ 0.8 × 10 9 produces an additional 20% increase in the total number of NCs per unit (V + PP [pr]; n = 1,269). The global increase achieved by the sum of the “twofraction” collection method and the processing restriction is 36%. Abbreviations: pnr, processing not restricted by cell content; PP, placental perfusion (fraction 2); pr, processing restricted to units ≥ 0.8 × 109 NCs; V, venipuncture (fraction 1).
Bornstein, Flores, Montalbán et al. enrich the cell content of the banked UCB units. In fact, the optimized collection method described here, together with the 0.8 × 10 9 NC processing limit, have resulted in a 36% increase in the NC content compared with the standard collection method (Fig. 7). The improvement in the NC content would result in an increment in the number of units clinically useful for adult patients. Indeed, 84% and 54% of our UCB units (compared with less than 30% units from other UCB banks) would fulfill the target dose of 2 × 10 7 NC for adult patients weighing 50 and 65 kg. Beside the improvement in the total cell content, this method provides around 15% increase in the number of committed HPC (CD34+ cells, CFU-GM and BFU-E) per unit. It is critical for the transplant centers to know if there is a correlation between CD34+ cells (or clonogenic progenitor cells) and NCs because the number of infused HPCs is more predictive of the time to neutrophil recovery and survival after UCBT than the total NCs [10, 53]. In the units stored in our bank we have found a linear correlation between CD34+ cells and NCs (r = .67, p = .01; data not shown). In addition, there is an increase in the number of CD133+ cells, a progenitor cell population that seems to be more enriched in pluripotent quiescent HSCs than CD34+ cells [54]. As a more primitive cell subset, functionally closer to the human long-term repopulating stem cell in vivo [55, 56], the higher CD133+ cell number may increase the hematopoietic reconstituting potential of our UCB units. Indeed, the preliminary results on eight patients transplanted with UCB units from our bank suggest that the two-fraction collection method may improve the clinical outcomes after UCBT. Four children and four adults were transplanted between September 2001 and February 2004. The children were 1–10 years of age (mean body weight, 19 kg), and the adults were 26–52 years of age (mean body weight, 61 kg). Total NCs infused were 5.66 × 10 7/kg (range 3.38–10.9) for children and 2.14 × 10 7/kg (range 1.82–2.85) for adult patients. The number of CD34 + cells infused was 2.15 (0.8– 6.0) × 10 5 /kg in children and 1.14 (0.58–2.0) ×10 5 /kg in adult patients. One adult patient died at day +14 from multiple organ failure. Neutrophil engraftment of 0.5 × 10 9 /1 was observed in the other seven patients with an average time of 23 days (range, 10–47). Five patients (three adults and two children) are alive with a median clinical follow-up of 15 months (range, 3–24 months). The overall survival at 2 years is 56% ± 20%. These preliminary results compare favorably to the overall survival rate (~ 45%) described with UCB units collected by the standard method [3, 4, 6–10]. The second fraction collected by placental perfusion may give rise to higher maternal cell contamination of UCB units that could cause life-threatening GVHD. In our study, three out of seven patients developed grades
331 II–IV acute GVHD (43%). One of them had grade IV acute GVHD (14%). These incidences are similar to those previously reported in patients transplanted with UCB collected by standard methods [3, 4, 6, 10], suggesting that the two-fraction collection method does not increase the risk of GVHD. We also determined the level of cord blood contamination by maternal cells in 20 UCB units stored at our bank. Locus-specific amplification of noninherited maternal HLA-DR genes was performed using polymerase chain reaction amplification followed by gel electrophoresis [57]. With a sensitivity limit of 1%, we did not detect maternal DNA in any of the 20 samples analyzed. Other studies using different techniques with a similar sensitivity have detected maternal cells in 0%–2% UCB units [38, 39]. Therefore, although we cannot rule out maternal cell contamination below 1%, it seems that the two-fraction collection method does not increase the frequency of cord blood contamination by maternal cells. The majority of UCB units stored in our bank were collected using a standard blood donor bag for each fraction, but the recent introduction of specific bags for UCB collection has greatly simplified the procedure. First, the volume of anticoagulant does not have to be reduced in advance. Second, both fractions are combined in the same container, thereby preventing possible errors in pooling fractions from different donors during subsequent processing. These advantages do not compromise the efficacy and higher UCB yields procured by the collection method described here. The two-fraction collection method and the processing restriction led to a NC content of 1.46 ± 0.52 × 10 9 per unit. This result is 39%–75% higher than UCB units collected by standard methods at several operative banks [24–26, 30–35, 58]. Other studies have tried to identify the optimal UCB collection techniques assessing the influence of mode of delivery (vaginal vs. cesarean) and harvest timing (before vs. after placental delivery) [31, 59–63]. Despite improved cell recovery claimed for certain procedures, the NC yields did not exceed the numbers reported by UCB banks [24–26, 30–35, 58]. One study successfully attempted to harvest larger units using a syringe-assisted “flush and drain” technique followed by umbilical arterial cathetherization and placental perfusion [58]. However, the associated bacterial contamination rate (19%) would prevent the use of this technique as a UCB harvest protocol for banking purposes. Of note, the volume and number of NCs in this study (174 ml and 1.69 × 10 9) were higher than ours, probably due to the increased amount of saline infused into the placenta (100 ml). Thus, it would be possible to retrieve even more blood just by flushing the placenta with larger saline perfusions. We will address this issue in a further cohort of UCB collections.
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Increased UCB Retrieval by Placental Perfusion
Conclusion
Acknowledgments
The higher hematopoietic potential of UCB units harvested and processed according to the methodology proposed in this study leads to an increase in the number of grafts with a 2 × 107/kg NC dose. Thus, 84% and 54% of our UCB units would fulfill this target dose in recipients weighing 50 and 65 kg compared with less than 30% units from other UCB banks. This significant advance procured by our novel UCB collection technique gives larger pediatric and many adult patients a greater chance of finding adequate grafts in order to achieve better clinical outcomes after UCBT.
This work was supported by grant nos. FIS 02/1877 from the Ministry of Health in Spain and 08.3/0037/2001 from the Education Department of the Autonomic Government of Madrid. We are grateful for the collaboration of the Department of Obstetrics of the Hospital 12 de Octubre, where all umbilical blood collections were performed. We would also like to thank C. Osborn for the review of the English version of the manuscript.
References 1 Wagner JE, Rosenthal J, Sweetman R et al. Successful transplantation of HLA-matched and HLA-mismatched umbilical cord blood from unrelated donors: analysis of engraftment and acute graft-versus-host disease. Blood 1996;88:795–802.
12 Rubinstein P, Carrier C, Carpenter C et al. Graft selection in unrelated placental/umbilical cord blood (PCB) transplantation: influence and weight of HLA match and cell dose on engraftment and survival. Blood 2000;96:588a.
2 Kurtzberg J, Laughlin M, Graham ML et al. Placental blood as a source of hematopoietic stem cells for transplantation into unrelated recipients. N Engl J Med 1996;335:157–166.
13 Stevens CE, Scaradavou A, Rubinstein P. Does patient age affect outcome in cord blood transplants? A retrospective analysis of 1101 transplants from the New York Blood Center’s National Cord Blood Program. Blood 2002;100:641a.
3 Gluckman E, Rocha V, Boyer-Chammard A et al. Outcome of cord-blood transplantation from related and unrelated donors. N Engl J Med 1997;337:373–381.
14 Sanz FG, Saavedra S, Planelles D et al. Standardized, unrelated donor cord blood transplantation in adults with hematologic malignancies. Blood 2001;98:2332–2338.
4 Rubinstein P, Carrier C, Scaradavou A et al. Outcomes among 562 recipients of placental-blood transplants from unrelated donors. N Engl J Med 1998;339:1565–1577.
15 Ooi J, Iseki T, Takahashi S et al. Unrelated cord blood transplantation for adult patients with advanced myelodysplastic syndrome. Blood 2003;101:4711–4713.
5 Thomson BG, Robertson KA, Gowan D et al. Analysis of engraftment, graft-versus-host disease, and immune recovery following unrelated donor cord blood transplantation. Blood 2000;96:2703–2711.
16 Ooi J, Iseki T, Takahashi S et al. Unrelated cord blood transplantation for adult patients with de novo acute myeloid leukemia. Blood 2004;103:489–491.
6 Rocha V, Cornish J, Sievers EL et al. Comparison of outcomes of unrelated bone marrow and umbilical cord blood transplants in children with acute leukemia. Blood 2001;97:2962–2971. 7 Locatelli F, Rocha V, Chastang C et al. Factors associated with outcome after cord blood transplantation in children with acute leukemia. Blood 1999;93:3662–3671. 8 Laughlin MJ, Barker J, Bambach B et al. Hematopoietic engraftment and survival in adult recipients of umbilical-cord blood from unrelated donors. N Engl J Med 2001;344:1815–1822. 9 Barker JN, Davies SM, DeFor T et al. Survival after transplantation of unrelated donor umbilical cord blood is comparable to that of human leukocyte antigen-matched unrelated donor bone marrow: results of a matched-pair analysis. Blood 2001;97:2957–2961. 10 Wagner JE, Barker JN, DeFor TE et al. Transplantation of unrelated donor umbilical cord blood in 102 patients with malignant and nonmalignant diseases: influence of CD34 cell dose and HLA disparity on treatment-related mortality and survival. Blood 2002;100:1611–1618. 11 Michel G, Rocha V, Chevret S et al. Unrelated cord blood transplantation for childhood acute myeloid leukemia: a Eurocord Group analysis. Blood 2003;102:4290–4297.
17 Gluckman E. Current status of umbilical cord blood hematopoietic stem cell transplantation. Exp Hematol 2000;28:1197–1205. 18 Rocha V, Chastang C, Laporte JP et al. Unrelated umbilical cord blood transplants in adults with hematologic malignancies. Blood 1998;92:144a. 19 Gluckman E. Hematopoietic stem-cell transplants using umbilical-cord blood. N Engl J Med 2001;344:1860–1861. 20 Laporte JP, Lesage S, Portnoï MF et al. Unrelated mismatched cord blood transplantation in patients with hematological malignancies: a single institution experience. Bone Marrow Transplant 1998;22(Suppl 1):S76–77. 21 Rocha V, Chastang C, Souillet G et al. Related cord blood transplant: the Eurocord experience from 78 transplants. Bone Marrow Transplant 1998;21(Suppl 3):S59–62. 22 Long GD, Laughlin M, Madan B et al. Unrelated umbilical cord blood transplantation in adult patients. Biol Blood Marrow Transplant 2003;12:772–780. 23 Barker J, Wagner JE. Umbilical-cord blood transplantation for the treatment of cancer. Nat Rev Cancer 2003;3:526– 532. 24 Kögler G, Sarnowski A, Wernet P. Volume reduction of cord blood by Hetastarch for long-term stem cell banking. Bone Marrow Transplant 1998;22(Suppl 1):S14–15.
Bornstein, Flores, Montalbán et al. 25 Querol S, Gabarró M, Amat L et al. The placental blood program of the Barcelona Cord Blood Bank. Bone Marrow Transplant 1998;22(Suppl 1):S3–5. 26 Jones J, Stevens CE, Rubinstein P et al. Obstetric predictors of placental/umbilical cord blood volume for transplantation. Am J Obstet Gynecol 2003;188:503–509. 27 Kögler G, Somville T, Göbel U et al. Haematopoietic transplant potential of unrelated and related cord blood: the first six years of the EUROCORD/NETCORD Bank Germany. Klin Pädiatr 1999;211:224–232. 28 Rubinstein P, Dobrila L, Rosenfield RE et al. Processing and cryopreservation of placental/umbilical cord blood for unrelated bone marrow reconstitution. Proc Natl Acad Sci U S A 1995;92:10119–10122. 29 Sutherland DR, Anderson L, Keeney M et al. The ISHAGE guidelines for CD34+ cell determination by flow cytometry. J Hematother 1996;5:213–226. 30 Prat I, Hernández C, Muñoz M et al. Organization of an umbilical cord blood transplant program. Haematologica 1998;83:667–669. 31 Donaldson C, Buchanan R, Webster J et al. Development of a district Cord Blood Bank: a model for cord blood banking in the National Health Service. Bone Marrow Transplant 2000;25:899–905. 32 Thierry D, Traineau R, Adam M et al. Hematopoietic stem cell potential from umbilical cord blood. Nouv Rev Fr Hematol 1990;32:439–440. 33 Davey S, Armitage S, Rocha V et al. The London Cord Blood Bank: analysis of banking and transplantation outcome. Br J Haematol 2004;125:358–365. 34 Reboredo NM, Díaz A, Castro A et al. Collection, processing and cryopreservation of umbilical cord blood for unrelated transplantation. Bone Marrow Transplant 2000;26:1263–1270. 35 Ballen KK, Wilson M, Wuu J et al. Bigger is better: maternal and neonatal predictors of hematopoietic potential of umbilical cord blood units. Bone Marrow Transplant 2001;27:7–14. 36 Rubinstein P, Taylor PE, Scaradavou A et al. Unrelated placental blood for bone marrow reconstitution: organization of the placental blood program. Blood Cells 1994;20:587–596. 37 Dal Cortivo L, Marolleau JP, Gluckman E et al. The Paris Cord Blood Bank. Bone Marrow Transplant 1998;22(Suppl 1):S11. 38 Socie G, Gluckman E, Carosella E et al. Search for maternal cells in human umbilical cord blood by polymerase chain reaction amplification of two minisatellite sequences. Blood 1994;83:340–344. 39 Briz M, Regidor C, Monteagudo D et al. Detection of maternal DNA in umbilical cord blood by polymerase chain reaction amplification of minisatellite sequences. Bone Marrow Transplant 1998;21:1097–1099. 40 Kurtzberg J, Graham M, Casey J et al. The use of umbilical cord blood in mismatched related and unrelated hemopoietic stem cell transplantation. Blood Cells 1994;20:275–283. 41 Kernan NA, Bartsch G, Ash RC et al. Analysis of 462 transplantations from unrelated donors facilitated by the National Marrow Donor Program. N Engl J Med 1993;328:593–602.
333 42 Szydlo R, Goldman JM, Klein JP et al. Results of allogeneic bone marrow transplants for leukemia using donors other than HLA-identical siblings. J Clin Oncol 1997;15:1767–1777. 43 Weisdorf DJ. Bone marrow transplantation for acute lymphocytic leukemia (ALL). Leukemia 1997;11(Suppl 4): S20–22. 44 Madrigal JA, Scott I, Arguello R et al. Factors influencing the outcome of bone marrow transplants using unrelated donors. Immunol Rev 1997;157:153–166. 45 Pecora AL, Stiff P, Jennis A et al. Prompt and durable engraftment in two older adult patients with high risk chronic myelogenous leukemia (CML) using ex vivo expanded and unmanipulated unrelated umbilical cord blood. Bone Marrow Transplant 2000;25;797–799. 46 Shpall EJ, Quinones R, Guiller R et al. Transplantation of ex vivo expanded cord blood. Biol Blood Marrow Transplant 2002;8:368–376. 47 Jaroscak J, Goltry K, Smith Aet al. Augmentation of umbilical cord blood (UCB) transplantation with ex-vivo expanded UCB cells: results of a phase I trial using the Aastrom Replicell system. Blood 2003;101:5061–5067. 48 Barker JN, Weisdorf DJ, Wagner JE. Creation of a double chimera after the transplantation of umbilical-cord blood from two partially matched unrelated donors. N Engl J Med 2001;344:1870–1871. 49 Fernández MN, Regidor C, Cabrera R et al. Unrelated umbilical cord blood transplants in adults: early recovery of neutrophils by supportive co-transplantation of a low number of highly purified peripheral blood CD34 + cells from an HLAhaploidentical donor. Exp Hematol 2003;31:535–544. 50 Rizzieri DA, Long GD, Vredenburgh JJ et al. Successful allogeneic engraftment of mismatched unrelated cord blood following a nonmyeloablative preparative regimen. Blood 2001;98:3486–3488. 51 Barker JN, Weisdorf DJ, DeFor TE et al. Rapid and complete donor chimerism in adult recipients of unrelated donor umbilical cord blood transplantation after reduced-intensity conditioning. Blood 2003;102:1915–1919. 52 Turner CW, Luzins J, Hutcheson C. A modified harvest technique for cord blood hematopoietic stem cells. Bone Marrow Transplant 1992;10:89–91. 53 Migliaccio AR, Adamson JW, Stevens CE et al. Cell dose and speed of engraftment in placental/umbilical cord blood transplantation: graft progenitor cell content is a better predictor than nucleated cell quantity. Blood 2000;96:2717–2722. 54 de Wynter E, Buck D, Hart C et al. CD34 + AC133 + cells isolated from cord blood are highly enriched in longterm culture initiating cells, NOD/SCID-repopulating cells and dendritic cell progenitors. Stem Cells 1998;16:387–396. 55 Goussetis E, Theodosaki M, Paterakis G et al. A functional hierarchy among the CD34 + hematopoietic cells based on in vitro proliferative and differentiative potential of AC133 + CD34bright and AC133dim/-CD34 + human cord blood cells. J Hematother Stem Cell Res 2000;9:827–840. 56 Handgretinger R, Gordon PR, Leimig T et al. Biology and
Increased UCB Retrieval by Placental Perfusion
334 plasticity of CD133 + hematopoietic stem cells. Ann N Y Acad Sci 2003;996:141–151. 57 Scaradavou A, Carrier C, Mollen N et al. Detection of maternal DNA in placental/umbilical cord blood by locus-specific amplification of the noninherited maternal HLA gene. Blood 1996;88:1494–1500. 58 Elchalal U, Fasouliotis SJ, Shtockheim D et al. Postpartum umbilical cord blood collection for transplantation: a comparison of three methods. Am J Obstet Gynecol 2000;182:227–232. 59 Screnci M, De Felice L, Carmini D et al. Does the type of delivery influence umbilical cord blood recovery? Bone Marrow Transplant 1995;16:631–632. 60 Surbek DV, Schönfeld B, Tichelli A et al. Optimizing cord
blood mononuclear cell yield: a randomized comparison of collection before vs. after placenta delivery. Bone Marrow Transplant 1998;22:311–312. 61 Surbek DV, Visca E, Steinmann C et al. Umbilical cord blood collection before placental delivery during cesarean delivery increases cord blood volume and nucleated cell number available for transplantation. Am J Obstet Gynecol 2000;183:218–221. 62 Solves P, Mirabet V, Larrea L et al. Comparison between two cord blood collection strategies. Acta Obstet Gynecol Scand 2003;82:439–442. 63 Kurtzberg J, Issitt L, Caravan H et al. Cord blood collections ex utero are no different to cord blood collections in utero when performed by trained collection staff. Cytotherapy 2003;5:437a.
