Kerecis (Iceland)

The extent and depth of burn injury may mandate temporary use of cadaver skin (allograft) to protect the wound and allow the formation of granulation tissue while split-thickness skin grafts (STSGs) are serially harvested from the same donor areas. However, allografts are not always available and have a high cost, hence the interest in identifying more economical, readily available products that serve the same function. This study evaluated intact fish skin graft (IFSG) as a temporary cover to prepare the wound bed for STSG application. Thirty-six full-thickness (FT) 5 × 5 cm burn wounds were created on the dorsum of six anesthetized Yorkshire pigs on day -1. To mimic the two-stage clinical situation, on day 0, wounds were excised down to a bleeding wound bed and a temporary cover (either IFSG or cadaver porcine skin) was applied; then, on day 7, wounds were debrided to a viable wound bed prior to the application of autologous 1.5:1 meshed STSG (mSTSG). Rechecks were performed on days 14, 21, 28, 45, and 60 with digital images, non-invasive measurements, and punch biopsies. The IFSG created a granulated wound bed receptive to the application of an mSTSG. FT burn wounds treated with an IFSG had similar outcome measures, including contraction rates, trans-epidermal water loss (TEWL) measurements, hydration, and blood perfusion levels, compared to cadaver skin-treated burn wounds. Pathology scoring indicated significant differences between the allograft- and IFSG-treated wounds on day 7, with the IFSG having increased angiogenesis, granulation tissue formation, and immune cells. Pathology scoring indicated no significant differences once mSTSGs were applied to wounds. The IFSG performed as well as cadaver skin as a temporary cover and was not inferior to the standard of care, suggesting the potential to transition IFSGs into clinical use for burns.

The scarcity of donor sites in patients with large burn wounds body highlights the need for more advanced treatments. Many tissue based products have been tested on burn wounds but with limited success due to poor integration and insufficient revascularization of the product. Fish skin grafts (KerecisTM Omega3) are naturally rich in Omega3 polyunsaturated fatty acids (PUFAs), which are precursors of the specialized pro-resolving lipid mediators (SPM) that modulate the immune response, tissue remodeling and of pain. Viral transmission risk is nonexistent from the Atlantic cod (Gadus morhua) preserving the intrinsic structure and biochemical composition. Clinical trials have shown that one such graft (Kerecis™ Omega3) significantly accelerates healing compared to a porcine matrix product. Separately, adipose derived stem cells (“ADSCs”) facilitate wound healing by enhancing cell migration and neovascularization, and may be incorporated into different grafts. The objective of this study was to evaluate the ability of fish skin graft to support ingrowth of ADSCs. ADSCs and fibroblasts were seeded (50,000 cells/cm2) onto 6 mm biopsy punches of fish skin in a 96 well plates. Growth medium was changed every 2 days, and samples were fixed on days 7, 14, 18 and 21 post-seeding. Samples, 2 µm in thickness were embedded in paraffin and H&E stained. Cell ingrowth was quantified with the ImageJ software. Vertical gridlines of 100 µm increments were created and ingrown cells within each grid counted. The acellular fish skin graft* supported and sustained three dimensional ingrowth of ADSCs for over 21 days in vitro. The number of ADSCs increased progressively across time and was 3.7 ± 0.6, (n=2) 9.8 ± 1.4 (n=3), 20 ± 2.6 (n=2), 22.4 ± 1.9 (n=3) and 29.4 ± 2.7 (n=2), at days 7, 10, 14, 18, and 21, respectively. Anova showed a significant difference between the groups (p=0,0004). Tukey post hoc testing revealed a significant difference between day 7 and all other points except day 10. Acellular fish skin supports and sustains three-dimensional ingrowth of ADSCs. Combination products including stem cells and fish skin graft may provide a novel and effective treatment for burn patients. ADSC based wound treatments are being developed but the best way to administer the ADSCs has not been determined. Fish skin seeded and cultured with autologous ADSCs could provide autologous, and non-immunogenic personalized wound coverage. This dual-action therapy may enhance burn healing via the benefits of the Omega3 derived SPMs and ADSCs.

Improvised explosive devices and new directed energy weapons are changing warfare injuries from penetrating wounds to large surface area thermal and blast injuries. Acellular fish skin is used for tissue repair and during manufacturing subjected to gentle processing compared to biologic materials derived from mammals. This is due to the absence of viral and prion disease transmission risk, preserving natural structure and composition of the fish skin graft. The aim of this study was to assess properties of acellular fish skin relevant for severe battlefield injuries and to compare those properties with those of dehydrated human amnion/chorion membrane. We evaluated cell ingrowth capabilities of the biological materials with microscopy techniques. Bacterial barrier properties were tested with a 2-chamber model. The microstructure of the acellular fish skin is highly porous, whereas the microstructure of dehydrated human amnion/chorion membrane is mostly nonporous. The fish skin grafts show superior ability to support 3-dimensional ingrowth of cells compared to dehydrated human amnion/chorion membrane (p < 0.0001) and the fish skin is a bacterial barrier for 24 to 48 hours. The unique biomechanical properties of the acellular fish skin graft make it ideal to be used as a conformal cover for severe trauma and burn wounds in the battlefield.