Cellular Invasion and Density in Perforated Acellular Dermal Matrices

BACKGROUND: Survival and durability of avascular tissue-replacement scaffolds depends on effective host cell invasion. There are several commercially available acellular dermal matrices (ADM) on the market, each with specific benefits and limitations. Considering that cellular invasion and vascularization are crucial in ADM incorporation and survival, any intervention that could potentially expedite this process should be explored. In this pilot study, we sought to quantitatively determine whether perforating ADM scaffolds would result in more effective host cell invasion in a murine model of graft incorporation.

METHODS:A total of four 6mm scaffolds of porcine ADM were obtained. Using a 26G needle, multiple perforations were made homogenously throughout the entire thickness of three scaffolds. One non-perforated scaffold served as a control. The scaffolds were implanted subcutaneously in the dorsa of C57BL6 mice and harvested after 14 days. The tissues were processed for histology, 10µm sections were obtained and stained with hematoxylin and eosin. Photos of each section were taken and then divided into equal depth layers . Mean cell density was systematically quantified through the depth of 4 layers and the results were compared using an unpaired t-test.

RESULTS:Statistical analysis of our data showed that while the mean cell density observed in the first layer was not different between perforated and non-perforated scaffolds (44.7 +/- 21.8 vs 44.7 +/- 16.8, p=0.99); perforated scaffolds showed a significantly higher mean cell density in the three deeper layers (28.6 +/- 22.6 vs 14.2 +/- 9.8, p<0.05; 18.6 +/- 20.5 vs 5.4 +/- 4.7, p<0.05; 12.3 +/- 15.0 vs 4.3 +/- 6.0, p<0.05) after 14 days.

CONCLUSION: We were able to demonstrate that perforated ADM has a significant advantage in cellular invasion and density when implanted in a suitable host, compared to non-perforated ADM, after only 14 days of implantation and may argue for incorporation of this simple step in the fabrication of or prior to clinical application of such scaffolds. Further studies using a larger sample size, determining the mechanical properties of perforated ADM, and comparing different types of ADM are needed. However, we believe these data show promising results in the quest for the optimal acellular dermal matrix.