To observe the biological characteristics of xenogeneic (porcine) acellular dermal matrix powder (ADMP), and explore the support of high purity and bioactive ADMP for the growth of epidermal cells and fibroblasts and its application in skin wound repair.

The back skin of Landrace was selected and decellularized by biological enzymatic method and freeze-dried to obtain xenogeneic (porcine) ADMP after being subjected to different cryogenic grinding procedures. Then, the sterile xenogeneic (porcine)ADMP was obtained by irradiation with ⁶⁰cobalt. The particle size and collagen morphology of HaCaT cells and BJ human skin fibroblasts with the cover of xenogeneic (porcine) ADMP were observed by scanning and transmission electron microscope, and the grinding program suitable for application was determined. The MTT was used to detect the adhesion efficiency of xenogeneic (porcine) ADMP cells in different concentrations, and the concentration range of xenogeneic (porcine) ADMP to achieve maximum adhesion was determined. DMEM medium was added with xenogeneic(porcine) ADMP as experimental group, and DMEM medium alone was used as control group. The real-time cellular analysis technology was used to analyze the migration index of BJ human skin fibroblasts, to verify the promotion of xenogeneic (porcine) ADMP on the fibroblasts. The primary epidermal cells were inoculated in xenogeneic (porcine) ADMP culture for 8 days and the proliferative curve was drawn to detect the proliferative effect of xenogeneic (porcine) ADMP on the primary epidermal cells. Meanwhile, immunofluorescence was used to detect the expression of the surface maturation and differentiation proteins of the primary epidermal cells. The data were compared with Student′s t-test.

After 1, 2, 3, 5, 7 and 10 cycles of the grinding procedure, xenogeneic (porcine) ADMP was obtained. All of which was white small powder, of which 1, 2, 3 cycle was large particles, 5, 7, 10 cycles showed a uniform concentrated trend. The particle size was distributed between 0 and 12 μm. The particle size of 5th cycle was (13.00±2.10) μm, compared with [(6.00±0.96) μm] of the 7th cycle, the difference was statistically significant (t=6.093, P=0.0002). Xenogeneic (porcine) ADMP transmission electron microscopy showed that xenogeneic (porcine) ADMP obtained in different cycle times can retain a large amount of collagen molecules. When BJ human skin fibroblasts and HaCaT cells were continusly enhanced, the concentration higher than 750 μg/cm^2, no significant changes. The real-time cellular analysis showed that the migration index of BJ human skin fibroblasts in the DMEM medium control group was 1.21±0.10 after 72 hours, while the migration index of the xenogeneic (porcine) ADMP medium group was 3.66±0.11, the difference was statistically significant (t=22.24, P=0.002). With the culture of xenogeneic (porcine) ADMP, the primary epidermal cells had a uniform form and rapid proliferation. A certain proportion of differentiated cells appeared in the control group. The number of cells in the experimental group and control group in the 5th day were (4.11±0.28)×10^5, (1.10±0.12)×10^5, the difference was statistically significant (t=13.51, P=0.005); in the 8th day the number of cells were (5.00±0.48)×10^5, (3.05±0.30)×10^5, the difference was statistically significant (t=4.87, P=0.039). The proliferation curve showed that the experimental group was in an exponential growth phase from the day of vaccination to the 5th day. Xenogeneic (porcine) ADMP cultured cells in the fluorescence staining system all expressed E-cadherin and expressed keratin 10 in small amounts, Integrin α6 was almost all strongly positive, keratin 14 was all expressed and some was strongly positive, Ki-67 antigen expression rate was high.

The xenogeneic (porcine) ADMP obtaineds by bio-enzymatic digestion and cryogenic grinding has the effect of promoting the proliferation and migration of two types of cells, epidermis and fibroblasts that are involved in the repair of skin wounds, and can be further applied to the repair of skin wounds in the future.