Pre-culture of adipose-derived stem cells and heterologous acellular dermal matrix: paracrine functions promote post-implantation neovascularization and attenuate inflammatory response. 
Heterologous acellular dermal matrix (ADM) has good biocompatibility and sufficient strength for clinical use for the repair of defects, tissue filling, and resurfacing of deep wounds.  However, ADM tissue has such a compact structure that it can easily result in delayed vascularization after implantation.  Moreover, in spite of the low immunogenicity of heterologous ADM, it can still cause varying degrees of inflammation in the host.  These two drawbacks limit the efficacy and scope of clinical applications for heterologous ADM.  Adipose-derived stem cells (ADSCs) have multiple effects on promoting vascularization and regulating immunological responses through paracrine signaling.  Pre-culturing heterologous ADM with ADSCs may address these problems; however, it is unknown if ADSCs can exert their paracrine functions within a heterologous ADM microenvironment.  This study examined the effect of porcine ADM (PADM) on the paracrine function of rat ADSCs (rADSCs) and showed that the expression of genes associated with inflammatory regulation, pro-angiogenesis factors, and stemness increased when rADSCs were seeded on PADM compared to rADSCs seeded on microplates.  This indicates that PADM can provide a beneficial microenvironment for ADSCs to exert their paracrine function.  After pre-culture, in vivo implanted rADSC-PADM exhibited improved vascularization and mitigated inflammatory response compared to untreated PADM.  This study is the first to report that ADM can provide a suitable microenvironment for ADSCs and that pre-culturing improved the ADM implantation quality in vivo.  These results suggest that it could be possible to apply heterologous ADM more effectively and broadly for repair and reconstruction treatments.