Genetically engineered human muscle transplant enhances murine host neovascularization and myogenesis

Abstract

Engineered tissues are a promising tool for addressing the growing need for tissues and organs in surgical reconstructions. Prevascularization of implanted tissues is expected to enhance survival prospects post transplantation and minimize deficiencies and/or hypoxia deeper in the tissue. Here, we fabricate a three-dimensional, prevascularized engineered muscle containing human myoblasts, genetically modified endothelial cells secreting angiopoietin 1 (ANGPT1) and genetically modified smooth muscle cells secreting vascular endothelial growth factor (VEGF). The genetically engineered human muscle shows enhanced host neovascularization and myogenesis following transplantation into a mouse host, compared to the non-secreting control. The vascular, genetically modified cells have been cleared for clinical trials and can be used to construct autologous vascularized tissues. Therefore, the described genetically engineered vascularized muscle has the potential to be fully translated to the clinical setting to overcome autologous tissue shortage and to accelerate host neovascularization and integration of engineered grafts following transplantation.

Enhanced Host Neovascularization of Prevascularized Engineered Muscle Following Transplantation into Immunocompetent versus Immunocompromised Mice

“…A previous study conducted by Koffler et al showed that 3 weeks post-implantation into abdominal wall defect, human ECs were almost completely replaced by mouse ECs and this was accompanied by a reduction in human capillary morphogenesis genes while angiogenic factors like VEGF and FGF-2 were still highly expressed [15]. In our previous studies, we used human ECs and human fibroblasts or smooth muscle cells to construct a vessel-like network within the engineered tissue that were transplanted into immunocompromised animals [8,9,15,16,18]. In the current study design, in order to transplant the engineered tissue into immunocompetent animals, we used murine ECs, SCs, and fibroblasts.…”

“…We have previously reported on successful transplantation of engineered vascularized muscle tissues, constructed on PLLA/PLGA scaffolds, into an abdominal wall musculature defect in immunocompromised mice [9,15,16,18,46]. Synthetic biodegradable PLLA/PLGA scaffolds, made from polymers approved for clinical use, were shown to promote vessel formation in vitro and to enable host vessel penetration in vivo [9,13,15,18].…”

“…The AIW was fabricated as previously described [16]. The AIW is made of a reusable stainless-steel ring (17 mm outer diameter, 13 mm inner diameter, and 2.3 mm thick), with a 1.3 mm groove on the side (Figure 2A).…”

“…While much progress has been made in the field of tissue engineering, most studies utilize immunocompromised animal models or administer immunosuppressive therapy to study the integration and survival of human engineered tissues in animals [8][9][10][11][12][13][14]. These works have established that in vitro graft prevascularization by human vascular cells is beneficial for graft integration and neovascularization post-implantation [8][9][10]13,[15][16][17]. It was also shown that culturing human vascular cells on biodegradable and biocompatible poly (l-lactic acid)/poly (lactide-co-glycolic acid) (PLLA/PLGA) scaffolds combined with fibrin gel results in the spontaneous formation of vessel-like structures in vitro, which later anastomose with the host vasculature upon transplantation into immunocompromised animals [9,16,18].…”

“…These works have established that in vitro graft prevascularization by human vascular cells is beneficial for graft integration and neovascularization post-implantation [8][9][10]13,[15][16][17]. It was also shown that culturing human vascular cells on biodegradable and biocompatible poly (l-lactic acid)/poly (lactide-co-glycolic acid) (PLLA/PLGA) scaffolds combined with fibrin gel results in the spontaneous formation of vessel-like structures in vitro, which later anastomose with the host vasculature upon transplantation into immunocompromised animals [9,16,18]. However, since the immune system plays a major role in the integration and vascularization of transplants within the host [19][20][21][22][23], such immunocompromised models fail to accurately reflect the responses elicited following autologous transplantation and under immunocompetent conditions.…”