Comparing the use of glycerol preserved and cryopreserved allogenic skin for the treatment of severe burns: differences in clinical outcomes and in vitro tissue viability

Abstract

Cryopreserved (CryoPA) and Glycerol-preserved (GPA) skin allografts are commonly used in the treatment of severe burn injuries. However, comparable data on their differences in clinical outcome is scarce. This retrospective review aims to study the effect of allograft viability on clinical outcomes. The records of 48 severe burn patients who either received CryoPA or GPA were reviewed. Key burn mortality determinants were used to match the 2 groups. Clinical outcomes such as mortality rate (MR) and the length of hospital stay (LOS) were obtained. A separate in vitro comparison included histological assessments and the use of tetrazolium reductase activity to compare tissue viability. Both groups showed a comparable profile in burn mortality determinants. Patients who received CryoPA had a lower MR of 25% compared to 34.8% (P=0.250) in the GPA group and a lower LOS of 39.2-45.9 days (P=0.730), respectively. The histological structural integrity was found to be well preserved with both methods although CryoPA was confirmed to be the more viable product (P<0.05). The lower MR associated with CryoPA cannot be totally ignored. However, the mechanism through which viable skin allografts improves MR of severe burns patients remains to be elucidated.

An outcome analysis and long-term viability of cryopreserved cultured epidermal allografts: assessment of the conservation of transplantable human skin allografts

“…In addition, in our study we utilized a cryoprotectant in order to improve the cell survival rate in cryopreservation. Similar as other authors 22,34,35 , the glycerol was utilized as cryoprotectant once this molecule enter the cells, reduce the ice crystal formation, thereby protecting cells from freezing lesion.…”

“…However, in recent study comparing the use of glycerol preserved and cryopreserved allogenic skin for the treatment of severe burns, the histological structural integrity observed that cryopreservation confirmed to be the more viable product 34 . Thus, questions about the possibility of cryopreservation for longer periods (up to 1 year) encouraged this study in terms of long-term cryopreservation.…”

Antimicrobial Effect of Skin for Allograft and Management in Burn Wound

“…CPA was carried out in a pre-warm 0.9% saline solution to thaw and rinsed away three times to remove cryoprotectant. Also GPA was rehydrated by soaking in saline solution at room temperature for 10 min and rinsed away three times [11].…”

“…Second, GPA refers to a method in which tissues are put in 85% Glycerol and the refrigerated at 2˚C -8˚C. This allograft is said to serve as a mechanical and physiological barrier and reduce the loss of protein and moisture, thereby preventing the bacterial infection [10] [11]. However, even though many studies have reported that skin protect pathogen by secreting the anti-microbial peptide (AMP) such as defensin, there has been very little research reported on the direct anti-microbial effectiveness of allograft.…”

Current insights into skin banking: storage, preservation and clinical importance of skin allografts

“…From their experience with burns, difficult wounds and leg ulcers, various authors agree that higher viability is associated with better wound-bed preparation and graft taking. 13,17,[33][34][35] Viable CSAs are deemed to have better transplant performance, to promote neovascularization, speed up healing, stimulate immunomodulatory response and reduce mortality risk. 13,14,[31][32][33][34][35][36] Some authors speculate that high cell viability may not be necessary for skin allograft function as a temporary dressing or permanent substitute.…”