Progenitor cells

THE DIFFERENCE IS IN DIFFERENTIATION: ELANIX PROGENITOR CELLS FOR TISSUE REGENERATION AND REPAIR

EXECUTIVE SUMMARY Progenitor cells are biological cells that

substance to the advantages of progenitor

share

cells enumerated at the outset. Section

characteristics

significantly

different

with, from

but

behave cells.

three examines the role of progenitor cells

This paper explores these differences and

stem

in tissue homeostasis and repair. Section

examines some of the arguments behind

four discusses the clinical precedents behind

Elanix Biotechnologies’ use of progenitor cells

Elanix’ technologies and provides information

for the development of products for tissue

about the biological bandages developed for

regeneration and repair, chief among which

the treatment of severe burn patients at

is their greater stability and predictability.

the Lausanne University Hospital (CHUV). In

After providing a cursory description of Elanix,

conclusion, section five briefly discusses the

the introduction describes some of the

direction in which Elanix is taking its product

advantages presented by progenitor cells for

development. Throughout this paper, the

tissue repair. Section two provides important

guiding thread is the advantage gained in

detail on the distinction between progenitor

using progenitor cells for tissue regeneration

cells and stem cells, and thus brings more

and accelerated wound healing solutions.

1.

Elanix Progenitor Cells

PROGENITOR CELLS FOR TISSUE REPAIR

Elanix Biotechnologies is a tissue

a general climate that tends to

more predictable, safer, and just as

regeneration company active in

give preference to stem cells in

effective. As will be discussed in more

the f ields of Advanced Wound

regenerative

research,

length in the following pages, fetal

Management and Advanced Skin

Elanix recognizes clear advantages to

progenitor cells have been observed

Care which aims to become an

the use of progenitor cells for targeted

to naturally initiate scarless healing

important player in the world of

indications. While progenitor cells

in

regenerative

core

have similar properties to stem cells

are exciting from a therapeutic

competence is the development of

and behave in a similar fashion,

perspective, and have fueled the

progenitor cell technology originating

they stand out mainly in their

biotechnological research of Elanix’

from and used for over 15 years

greater predictability, which makes

scientific team for several decades.

within the Burn Unit at the Lausanne

them easier to manipulate and

University

medicine.

Its

medicine

CHUV

work with in culture. In addition,

Universitaire

this also considerably reduces risks

Vaudois) in Lausanne, Switzerland.

related to undesirable or unplanned

The activities of Elanix Biotechnologies

differentiation. These considerations

are predicated upon the potential

explain the underlying rationale for

of

choosing progenitor cells as the basis

(Centre

Hospital Hospitalier

progenitor

regeneration

cells

or

for

products.

tissue Within

for

tissue

regeneration

the

womb.

These

properties

products:

2.


DISTINGUISHING PROGENITOR CELLS FROM STEM CELLS

are still concerns regarding their Stem cell and progenitor cell terminology is often confusing

tumor-inducing

potential

once

in the literature because both terms are f requently used to

implanted in vivo. It is known that

describe adult stem cells. Progenitor cells, however, are not

in vitro differentiated stem cells can

stem cells! While it is true that stem cells and progenitor cells

significantly lack stability. They can

share some biological characteristics, they also differ in several

de-differentiate and, depending on

important ways:

their environment, start multiplying or differentiating into other unplanned cell

Embryonic stem cells, adult stem cells, and progenitor cells: Embryonic stem cells, commonly

such as bone marrow, placenta, skin

referred to simply as stem cells,

or adipose tissue (1, 2). The cells are

can be isolated from early stage

multipotent, meaning that they are

embryos (< 2 weeks). These are

able to differentiate into a number

undifferentiated,

that

of cell types (neurons, chondrocytes,

they do not represent any specif ic,

osteoblasts)(3,4,5) depending on the

specialized adult cell type. In other

factors present in their environment.

words, for example, they have not

Adult

yet committed to becoming liver,

advantages over embryonic stem

bone, or skin cells. They have

cells: tissue for cell isolation can

high self-renewal and proliferation

easily be obtained, higher numbers

capacities

totipotent,

of stem cells are isolated from a

meaning they can differentiate into

single tissue biopsy, and thus in vitro

any

a

culture conditions are significantly

new organism in vivo. While the

less demanding and less costly.

potential of in vitro engineered

These properties are highly attractive

product

where the goal is to create in vitro

this

type

and of

meaning

are

cell

and

development

unlimited

form

is

high,

differentiation

stem

biological

cells

structures

have

to

risk

of adult stem cells have long and

teratoma

formation, a kind of tumor.

tumorous

replace

damaged tissues. Certain varieties

with

including

several

capacity is also the basis for the associated

types,

formations (6).

successful records of clinical use, such as the bone marrow transplant,

Adult stem cells can be identified

which have been performed for

and isolated from different tissues

over

40

years.

However,

there

3.


Progenitor cells are early descendants of stem cells. Progenitor cell reservoirs are found in many adult tissues such as the brain, blood system, skin, or intestine (7,8) where they participate in tissue homeostasis and tissue repair (9). They can also be ethically isolated from human fetuses between 9 and 14 weeks in the eventuality of a voluntary interruption of a pregnancy. In contrast to stem cells, progenitor cells do not self-renew and are highly restricted in their differentiation (10,7,11,12). This means that specific progenitor cells will only develop into their intended cell types and do not present the same unpredictability as stem cells. This is of major importance to the safety of their usage in biotechnology as it significantly reduces the risk of tumor formation. Overall, progenitor cells are stable, easy to handle in culture, and their high proliferation potential allows the generation of cell banks for biological applications (10,13,14). For all these reasons, fetal progenitor cells have been used for the production of different vaccines for decades such as the polio vaccine, and research is ongoing to use the same fetal progenitor cells as feeder cells for keratinocyte expansion in the treatment of burn patients (15,16).

One donation

Bone cells Skin cells

Tendon cells

Cartilage cells

Muscles cells

Disque cells

4.


THE ROLE OF PROGENITOR CELLS IN TISSUE HOMEOSTASIS AND REPAIR

The underlying biological mechanisms

seen, for example, in chronic wounds

differentiating

to

replenish

the

of tissue homeostasis and repair are

that never manage to fully heal and

cellular pool on an ongoing basis.

complex processes which are not

pose significant health risks in the

yet fully understood. We do know

long- term.

Two main mechanisms of action

however that both stem cells and

have been proposed for stem cells

progenitor cells are involved and play

This description of the body’s natural

a key role in ensuring the successful

response to the trauma of a new

outcome of this natural process.

wound demonstrates how important

A)

the stem and progenitor cells are

homeostasis,

Upon injury, the tissue repair system

in the healing process. One of the

proliferate and terminally differentiate

is readily activated and involves the

initiators and part of the coagulation

to produce new tissue (9,12,17,18).

very precise coordination of multiple

cascade are platelets, which serve as

cell types to successfully heal tissue.

reservoirs releasing all kinds of factors

B) adult stem cells and progenitor

This is well observed in wound

that attract and influence these cells.

cells help tissue recovery through

healing where the body’s response

and progenitor cells in tissue repair. in

order

paracrine

to

maintain

progenitor

activity:

tissue cells

endothelial

starts in a matter of seconds after

Consider, for example, the case of

progenitor cells have been shown to

the wound with the activation of the

tissues with a high cell turnover

secrete angiogenic growth factors

coagulation cascade to stop blood

such as skin, intestine, or blood. The

which induce neovascularization, fetal

loss, followed by the recruitment of

lifespan of keratinocytes and red

progenitor cells have been shown to

immune cells to clear pathogens

blood cells is only 30 days and 120

improve adipose-derived stem cell

and cellular debris, the activation of

days, respectively. As a result, these

growth in co-culture experiments,

skin cells for reepithelization which

tissues must constantly be renewed

and amniotic epithelial cells produce

leads, in turn, into the process of scar

to maintain tissue homeostasis and

exosomes that stimulate fibroblast

maturation. Improper coordination

functionality. Progenitor cells present

proliferation and migration in vitro

between the different cell types or

in these tissues provide this function

(19,20,21,22).

stages results in inefficient repair as

by

multiplying

and

terminally

5.


CLINICAL PRECEDENTS: PROGENITOR FETAL CELL EXTRACTS FOR WOUND HEALING SOLUTIONS

During

their

early

gestational

development, from the appearance of fetal progenitor cells until week 24, fetuses have the ability to heal

Before treatment

skin wounds rapidly and without scarring. This particularity is not due to the uterus environment but rather

15-20 mo follow-up

to properties intrinsic to fetal skin cells (23,24). The exact mechanisms involved in this highly efficient repair have not yet been fully elucidated

8-9 yr follow-up

(25). Understanding the differences between fetal and adult wound healing properties is of particular

These biological dressings are not

today, they still require accredited

interest for the scientific community

tissue grafts, as the progenitor cells

infrastructures for cell storage and

as it could open strategies for the

cannot be found in patient tissue

cell manipulation. As live progenitor

development of new therapeutic

after healing. However, surgeons

cells are used, the biological dressing

products for the treatment of acute

observe an improvement in the

shelf life is short.

and chronic wounds.

healing process due to a reduction of pain, a reduced need for skin grafts,

In

The Burn Unit at the CHUV developed

and an improved scar quality. A

by Lapp et al. (2013), a further

custom made biological bandages

10-year follow-up study of the first

biopharmaceutical formulation was

using fetal progenitor cells for the

pediatric

developed by integrating ovine fetal

treatment of second degree burns.

progenitor cells demonstrated the

progenitor cell extracts(28).

These are currently used under a

safety of the treatment as well as the

The progenitor cellular extract was

compassionate use exemption (26).

significantly improved viscoelastic

shown to induce dermal fibroblast

The dressings consist of fetal skin

properties of the skin( ).

proliferation in vitro demonstrating

patients

treated

with

27

addition,

as

documented

that the extract is biologically active.

progenitor cells stored in liquid production

The extract was incorporated in

seeded in a collagen matrix, and

is routinely used in the CHUV for

an oil-in-water cream and used

delivered to the patient within 24-48

severe burn patients. They require

topically on acute wounds (incision

hours. The dressings are changed

cGMP facilities and cannot be stored

or burns). Upon topical application,

every three days (with 3 to 6

once produced which highly restricts

rapid

applications depending on extent

the development potential of such

inflammation was observed.

and severity of the burn injury).

products. In the form they are used

nitrogen

which

are

revitalized,

Biological

bandage

wound

closure

with

low

6.


BRINGING PROGENITOR CELL BASED SOLUTIONS TO THE WORLD

Elanix Biotechnologies is built on the

development for the wound care

soothe intimate discomfort, twinges,

conviction that progenitor cells have

management market. Under the

and feelings of dryness. SKINrepair® is

an important role to play in the future

project name FirstCover, Elanix is

formulated for application on the skin

of regenerative medicine. This paper

developing medical devices from

to soothe lesions, help regenerate

has set out to clarify somewhat the

fetal progenitor cell technology to

the epidermis, and accompany the

nature of progenitor cells and their

assist and accelerate the wound

process of scar management.

natural role in homeostasis and tissue

healing process in patients suffering

repair, and to provide some evidence

not only from severe burns, but also

to support the adoption of progenitor

from diabetic foot, pressure ulcers,

cells for the development of tissue

and venous leg ulcers, all of which are

regeneration products.

currently underserved conditions.

The progenitor cell technology at the heart of Elanix Biotechnologies has

Elanix

aims

to

transform

the

The company’s current portfolio consists

been systematically proven to be safe,

experience gained in the use of

of Advanced Skin Care products

without known side-effects or adverse

biological wound dressings, a tech-

GYNrepair

reactions,

nology for highly controlled clinical

contain the CFPC®, a cell free protein

positive results towards its intended

environments, into products that

extract from animal progenitor cells.

goal: the acceleration of natural

can be distributed widely, easily

These products are directly derived

tissue regeneration. Elanix’ mission is

and durably stocked with no loss of

from Professor Applegate’s research

to replicate these successful results

efficacy, and applied successfully with

(28, 29) and are shown to relieve patients’

in the products which it brings to

relative ease. This industrialization

symptoms and promote healing.

market. These technologies have the

process is what Elanix is tackling

GYNrepair® is formulated for the

potential to bring significant benefit

in its current phase of product

external genital mucosa and used to

to patients worldwide.

®

and SKINrepair , which ®

and

has

yielded

very

7.


REFERENCES

1.

Zuk, P. A. et al. Multilineage cells from human adipose tissue: implications for cell-based therapies. Tissue Eng. 7, 211–228 (2001).

2.

Cavallo, C. et al. Comparison of alternative mesenchymal stem cell sources for cell banking and musculoskeletal advanced therapies. J. Cell Biochem. 112, 1418–1430 (2011).

3.

Kappos, E. A. et al. Peripheral Nerve Repair: Multimodal Comparison of the Long-Term Regenerative Potential of Adipose Tissue-Derived Cells in a Biodegradable Conduit. Stem Cells Dev. 24, 2127–2141 (2015).

4.

Bunnell, B. A., Flaat, M., Gagliardi, C., Patel, B. &; Ripoll, C. Adipose-derived Stem Cells: Isolation, Expansion and Differentiation. Methods. 45, 115–120 (20008).

5.

Zhu, X., Shi, W., Tai, W. & Liu, F. The comparition of biological characteristics and multilineage differentiation of bone marrow and adipose derived Mesenchymal stem cells. Cell Tissue Res. 350, 277–287 (2012).

6.

Faroni, A., Smith, R. J. P., Lu, L. & Reid, A. J. Human Schwann-like cells derived from adipose-derived mesenchymal stem cells rapidly de-differentiate in the absence of stimulating medium. Eur. J. Neurosci. 43, 417–430 (2016).

7.

Seaberg, R. M. & Van Der Kooy, D. Stem and progenitor cells: The premature desertion of rigorous definitions. Trends Neurosci. 26, 125–131 (2003).

8.

Hirt-Burri, N. & Applegate, L. A. Hirt Burri and Applegate Fetal Muscle cell therapy 2013.pdf. (2013).

9.

Nakatomi, H. et al. Regeneration of hippocampal pyramidal neurons after ischemic brain injury by recruitment of endogenous neural progenitors. Cell. 110, 429–441 (2002).

10. Grognuz, A., Scaletta, C., Farron, A., Raffoul, W. & Applegate, L. A. Human Fetal Progenitor Tenocytes for Regenerative Medicine. Cell Transplant. 25, 463–479 (2016). 11.

Akashi, K., Traver, D., Miyamoto, T. & Weissman, I. L. A clonogenic common myeloid progenitor that gives rise to all myeloid lineages. Nature. 404, 193–197 (2000).

12. Barber, C. L. & Iruela-Arispe, M. L. The ever-elusive endothelial progenitor cell: Identities, functions and clinical implications. Pediatr. Res. 59, 26–32 (2006). 13. Darwiche, S., Scaletta, C., Raffoul, W., Pioletti, D. P. & Applegate, L. A. Epiphyseal Chondroprogenitors Provide a Stable Cell Source for Cartilage Cell Therapy. Cell Med. 4, 23–32 (2012).

8.


14. Quintin, A. et al. Consistency and safety of cell banks for research and clinical use: preliminary analysis of fetal skin banks. Cell Transpl. 16, 675–684 (2007). 15. Bullock, A. J., Higham, M. C. & MacNeil, S. Use of human fibroblasts in the development of a xenobiotic -free culture and delivery system for human keratinocytes. Tissue Eng. 12, 245–255 (2006). 16. Friedman, H. M. & Koropchak, C. Comparison of WI-38, MRC-5, and IMR-90 cell strains for isolation of viruses from clinical specimens. J. Clin. Microbiol. 7, 368–371 (1978). 17. Jiang, S. et al. Transplanted human bone marrow contributes to vascular endothelium. Proc. Natl. Acad. Sci. USA. 101, 16891–6 (2004). 18. Jeffrey Crosby & Bowen-Pope, D. F. Endothelial Cells of Hematopoietic Origin Make a Significant Contribution to Adult Blood Vessel Formation. Circ. Res. 87, 728–730 (2000). 19. Rehman, J., Li, J., Orschell, C. M. & March, K. L. Peripheral blood ‘endothelial progenitor cells’ are derived from monocyte/macrophages and secrete angiogenic growth factors. Circulation. 107, 1164–1169 (2003). 20. Krähenbühl, S. M., Grognuz, A., Michetti, M., Raffoul, W. & Applegate, L. A. Enhancement of Human Adipose-Derived Stem Cell Expansion and Stability for Clinical use ClinMed. (2015). 21. Kalka, C. et al. Transplantation of ex vivo expanded endothelial progenitor cells for therapeutic neovascularization. Proc. Natl. Acad. Sci. USA. 97, 3422–3427 (2000). 22. Zhao, B. et al. Exosomes derived from human amniotic epithelial cells accelerate wound healing and inhibit scar formation. J. Mol. Histol. 48, 121–132 (2017). 23. Bullard, K. M., Longaker, M. T. & Lorenz, H. P. Fetal wound healing: Current biology. World J.Surg. 27, 54–61 (2003). 24. Armstrong, J. R. & Ferguson, M. W. J. Ontogeny of the skin and the transition from scar-free to scarring phenotype during wound healing in the pouch young of a marsupial, Monodelphis domestica. Developmental Biology. 169, 242–260 (1995). 25. Manuscript, A. NIH Public Access. Plast. Reconstr. Surg. 126, 1172–1180 (2014). 26. Hohlfeld, J. et al. Tissue engineered fetal skin constructs for paediatric burns. Lancet. 366, 840–842 (2005). 27. De Buys Roessingh, A. H.-B. N. R. W. S. C. A. L. A. A decade after foetal skin progenitor cell therapy in pediatric burn treatment. J. Regen Med. 4, 1–5 (2015). 28. Lapp A Ramelet A, Aubort C, Aubort P, Laurent P, Applegate LA, F. P. Cellular Derivatives and Efficacy in Wound and Scar Management. JCDSA. 3, 36–45 (2013). 29. Hirt-Burri, N. et al. Biologicals and fetal cell therapy for wound and scar management. ISRN Dermatol. 2011, 549870 (2011).

9.