Research

Effects of glycerol

Euro Skin Bank has started several research projects since 1980. The effects of glycerol 85% on the morphology of donor skin and the in-activation of micro-organisms were investigated. In addition, the clinical effectiveness was studied.

The clinical use of glycerol preserved donor skin is comparable with cryo-preserved skin. After removal of the glycerol, the donor skin can be used as a temporary biological dressing for partial thickness wounds (1), full thickness burns after removal of non-vital tissue or as coverage for widely expanded autografts (2, 3). It is also possible to combine the donor skin with cultured keratinocytes (4). Kreis et al. described (5, 6) consistent results using glycerol preserved donor skin as coverage for 1:6 or 1:9 expanded autologous split skin islands, with good survival rates for the autologous skin grafts. The majority of the operations resulted in > 95% re-epithelialisation.

Although no comparative studies are published, experiences in hospitals indicate glycerol preserved donor skin functions in the same way as cyro-preserved donor skin in clinical use. The rejection process is supposed to be attenuated since the donor cells are non-viable. The cells in glycerol-preserved cadaver skin are dead but their morphology is well-preserved. (7)In standard light microscopy preparations no differences could be observed in structural integrity compared with fresh skin, although some shrinkage of keratinocytes is described. Matrix morphology appears to be intact.

Recent studies into the role of skin dendritic cells in skin immunology suggest a mechanism to explain the clinical impression that glycerol preserved is less immunogenic than cryopreserved skin. The known migratory characteristics of dendritic cells including Langerhans cells are absent, presumably because in glycerol preserved the cells are nonviable. After transplantation, Langerhans cells can not migrate to the draining lymph nodes where activation of T cells takes place. Furthermore in contrast to fresh skin, homogenates of glycerol-preserved skin fail to invoke a response when incubated with allogeneic T-cells; only when other antigen-presenting cells such as monocytes are added can an attenuated response be obtained ( 8, 9, 10 )The rejection process is delayed until the antigen presenting cells such as monocytes come into contact with allogeneic tissue via the ingrowing blood vessels. Experiments in a porcine model show rejection of glycerol preserved allogeneic skin is delayed up to 6 days compared with fresh allogeneic skin (11)

Glycerol is a slow but effective bactericide; 97% of bacteriologic cultures from GPA are negative within 3 months. The inactivation of micro-organisms is enhaced by the addition of antibiotics during processing (12, 13 )Glycerol 85% can also inactivate viruses. Studies by Van Baare et al (14) indicate that the antiviral properties of glycerol are principally dependent on glycerol concentration, temperature, and duration of exposure. Herpes simplex was inactivated fast at 37 ºC but much slower at 4ºC (14, 15). Free HIV-1 was inactivated within 1h at 37°C with 85% glycerol. Storage of exogenously HIV-1 infected cadaver skin in 85% glycerol at 4°C resulted in complete inactivation of the virus after five days (16).

Although some viruses may be inactivated by the current manufacturing process, further validation research must define the optimal processing conditions for virus elimination. Available data suggest that the possibility of virus transmission with GPA as now manufactured cannot be discounted. On the other hand, each year over 1.550.000 cm² GPA have been used clinically by burn centres in Europe, with no reports of suspected disease transmission.
Transmission of micro-organisms via donor skin cannot be ruled out completely with the current state of knowledge but by careful donor selection the risk is very low.

Further progress with synthetic skin substitutes may eventually render the use of skin allografts in burn care redundant. In the meantime, the low costs of manufacture combined with ease of handling ensure that glycerol preserved donor skin still has a useful role in the clinical treatment of burn injuries. For larger scald burns, it is still preferred above hydrofibre dressings (17).

New developments, Glyaderm

Although treatment with donor skin stimulates the healing of the wound, the quality of the final scar is still disappointing. Especially deep wounds treated with widely expanded autologous skin heal with contraction and hypertrophic scars. Dermal substitution may improve the final result. Since 2000 research has been done by ESB to develop a dermal substitute from donor skin. A prototype was prepared using low concentrations of NaOH. All donor cells are removed effectively using this method, the remaining acellular dermis consists of collagen and elastin fibres and can therefore be used as implant instead of a biological coverage. This prototype (Glyaderm) could effectively reduce wound contraction (18) in experimental models.

GLYADERM is Glycerol preserved acellular donor dermis, therefore no rejection process will occur after implantation under the autologous split skin. It can be used to replace the dermal tissue lost by the burn to increase the scar quality (19). Results of an intra-individual comparative clinical study show the elasticity of the scar is improved compared to part of the wound treated with only split skin, at 1 year after treatment (20, 21). A multi-center study has been performed to study both clinical and cost-effectivity effects of GLYADERM (www.glyaderm.org). The positive results were presented at the EBA congress in Vienna (2013). Long term follow up results of the scars (4-6 years after operation) showed further improvement during time with good pliability. Glyaderm is now available for clinical use.

References

  1. Hermans MHE. Clinical experience with glycerol preserved donor skin treatment in partial thickness burns. Burns 1989; 15: 57-60.

  2. Kreis RW, Vloemans AFPM., Hoekstra MJ, Mackie DP, Hermans RP. The use of non-viable glycerol-preserved cadaver skin combined with widely expanded autografts in the treatment of extensive third-degree burns. J Trauma 1989; 29:51-55.

  3. Kreis RW, Mackie DP, Vloemans AFPM, Hoekstra MJ. Widely expanded postage stamp skin grafts using a modified Meek technique in combination with an allograft overlay. Burns 1993; 19: 142-145.

  4. Schiozer WA, Hartinger A, Henkel v. Donnersmarck G, Muhlbauer W. Composite grafts of autogenic cultured epidermis and glycerol-preserved allogeneic dermis for definitive coverage of full-thickness burn wounds: case reports. Burns 1994; 20: 503-507.

  5. Meek CP. Extensive severe burn treated with enzymatic debridement and microdermagrafting. Am Surgeon 1963; 29: 61-64.

  6. Kreis RW, Mackie DP, Hermans RP, Vloemans AFPM. Expansion techniques for skin grafts: comparison between mesh and Meek island (sandwich-) grafts. Burns 1994; 20; S39-42. 

  7. Richters CD, Hoekstra MJ, van Baare J, du Pont JS, Kamperdijk EWA. Morphology of glycerol-preserved human cadaver skin. Burns 1996; 22: 113-116.

  8. Richters CD, Hoekstra MJ, van Baare JS, Kamperdijk EWA. Rat monocyte-derived dendritic cells function and migrate in the same way as isolated tissue dendritic cells. J Leukoc Biol. 2002; 71:582-587.

  9. Richters CD, Hoekstra MJ, Van Baare J, Du Pont, Kamperdijk EWA. Immunogenicity of glycerol-preserved human cadaver skin in vitro. J Burn Care & Rehabilitation 1997; 18: 1-8.

  10. Richters CD, Van Gelderop, du Pont JS, Hoekstra MJ, Kreis RW, Kamperdijk EWA. Migration of dendritic cells to the draining lymph node after allogeneic or congeneic rat skin transplantation. Transplantation, 1999, 67(6); 828-832.

  11. Richters CD, Hoekstra MJ, du Pont JS, Kreis RW, Kamperdijk EWA. Immunology of skin transplantation. Clinics in Dermatology 2005; 23:338-342.

  12. Saegeman V.S.M, Ectors NL, Lismont D, Verduyckt B, Verhaegen J. Short- and long-term bacterial inhibiting effect of high concentrations of glycerol used in the preservation of skin allografts. Burns 2008; 34: 205-211.

  13. Van Baare J, Ligtvoet EEJ, Middelkoop E. Microbiological evaluation of glycerolised cadaveric donor skin. Transplantation 1998; 65: 966-970.

  14. Van Baare J, Buitenwerf J, Hoekstra MJ, du Pont JS. Virucidal effect of glycerol as used in donor skin preservation. Burns 1994; 20: S77-S80.

  15. Marshall L, Gosh MM, Boyce SG, MacNeill S, Freedlander E, Kudesia G. Effects of glycerol on intracellular virus survival: implications for the clinical use of glycerol-preserved cadaver skin. Burns 1995; 21:356-361.

  16. Cameron PU, Pagnon JC, Van Baare J, Reece CR, Vardaxis NJ, Crowe SM. Efficacy and kinetics of glycerol inactivation of HIV-1 in split skin grafts. J Med Virol 2000; 60:182-188.

  17. Vloemans AF, Soesman AM, Suijker M, Kreis RW, Middelkoop E. A randomised clinical trial comparing a hydrocolloid-derived hydrofibre and glycerol preserved allograft skin in the management of thickness burns. Burns 2003; 29: 702-210.

  18. Richters CD, Pirayesh A, Hoeksema H, Kamperdijk EWA, Kreis RW, Dutrieux RP, Monstrey S, Hoekstra MJ. Development of a dermal matrix from glycerol preserved allogeneic skin. Cell Tissue Bank 2008; 9: 309-315.

  19. Brusselaers N, Pirayesh A, Hoeksema H, Richters CD, Verbelen J, Beele H, Blot SI, Monstrey S. Skin replacement in burn wounds. J Trauma. 2010;68:490-501.

  20. Pirayesh A, Richters CD, Hoeksema H, Verbelen J, Heyneman A, Monstrey S. 2011 Clinical evaluation of glyaderm, a dermal substitute based on glycerinized donor skin. In: Skin grafts, book chapter, 291-298. InTech, Editor Dr. Marcia Spear. ISBN 978-953-308-958.

  21. Pirayesh A, Hoeksema H, Richters C, Verbelen J, Monstrey S. Glyaderm® dermal substitute: Clinical application and long-term results in 55 patients. Burns 2015 Feb;41:132-44.

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