Complex 3D Skin-for-Skin Microstructure of Fish Skin Grafts is Ideal for Cellular Colonization

Background

Most cellular and tissue based products (CTPs) are derived from livestock or human amniotic membranes and require heavy processing due to disease transmission risk. This removes bioactive components and denatures microstructure, leaving behind only a matrix of the most insoluble collagens.(1,2)

Fish skin grafts* CTPs undergo gentler processing methods since they (Gadus morhua) do not pose a disease transmission risk to humans,(3) preserving bioactive components and skin-for-skin microstructure.(4,5)

Fish skin grafts* are rich in omega-3 EPA and DHA fatty acids, necessary for biosynthesis of the specialized pro-resolving lipid mediators (SPMs) that orchestrate inflammation resolution and are lacking in chronic wounds.(6,7)

AIM

To assess the microstructure and cellular interactions in different types of CTPs.

METHODS

Structure was examined with scanning electron microscopy. Cell ingrowth was studied by seeding NIH 3T3 fibroblasts (ATCC, CRL-1658™) onto CTPs in multi-well plates and examine slides with confocal (Olympus FV1200) microscopy. Cell ingrowth quantification was done with ImageJ software(8) Independent samples t - test in R.(9) Wound healing assay: Culture Insert 2 well (Ibidi GmbH) using HaCaT keratinocytes (ATCC® PCS-200-010™).

RESULTS

SEM images revealed differences in the microstructure of the tissues investigated. The fish skin graftA is highly porous with pore size (10-150 µm diameters) while the other CTPs are thinner, packed due to processing, or peeled. Grafts from acellular fish skinsA facilitate significantly (p<0.0001) more cell ingrowth compared to amnion/chorion membraneB that mostly had a single cell layer growing on top of the scaffold. Fish skinA provides excellent attachment for seeded fibroblast. Follow-up studies showed that the fish skin graftsA lipids improved keratinocyte migration in response to injury.

CONCLUSION

Microstructure of fish skin grafts is highly porous and resembles human skin. The other CTPs were lacking in microstructure due to tissue origin or processing. Complex and porous microstructure is vital for cellular colonization.