Angiogenic properties of dehydrated human amnion/chorion allografts: therapeutic potential for soft tissue repair and regeneration

Abstract

BackgroundChronic wounds are associated with a number of deficiencies in critical wound healing processes, including growth factor signaling and neovascularization. Human-derived placental tissues are rich in regenerative cytokines and have been shown in randomized clinical trials to be effective for healing chronic wounds. In this study, PURION® Processed (MiMedx Group, Marietta, GA) dehydrated human amnion/chorion membrane tissue allografts (dHACM, EpiFix®, MiMedx) were evaluated for properties to support wound angiogenesis.MethodsAngiogenic growth factors were identified in dHACM tissues using enzyme-linked immunosorbent assays (ELISAs), and the effects of dHACM extract on human microvascular endothelial cell (HMVEC) proliferation and production of angiogenic growth factors was determined in vitro. Chemotactic migration of human umbilical vein endothelial cells (HUVECs) toward pieces of dHACM tissue was determined using a standard in vitro transwell assay. Neovascularization of dHACM in vivo was determined utilizing a murine subcutaneous implant model.ResultsQuantifiable levels of the angiogenic cytokines angiogenin, angiopoietin-2 (ANG-2), epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), heparin binding epidermal growth factor (HB-EGF), hepatocyte growth factor (HGF), platelet derived growth factor BB (PDGF-BB), placental growth factor (PlGF), and vascular endothelial growth factor (VEGF) were measured in dHACM. Soluble cues promoted HMVEC proliferation in vitro and increased endogenous production of over 30 angiogenic factors by HMVECs, including granulocyte macrophage colony-stimulating factor (GM-CSF), angiogenin, transforming growth factor β3 (TGF-β3), and HB-EGF. 6.0 mm disks of dHACM tissue were also found to recruit migration of HUVECs in vitro. Moreover, subcutaneous dHACM implants displayed a steady increase in microvessels over a period of 4 weeks, indicative of a dynamic intra-implant neovascular process.ConclusionsTaken together, these results demonstrate that dHACM grafts: 1) contain angiogenic growth factors retaining biological activity; 2) promote amplification of angiogenic cues by inducing endothelial cell proliferation and migration and by upregulating production of endogenous angiogenic growth factors by endothelial cells; and 3) support the formation of blood vessels in vivo. dHACM grafts are a promising wound care therapy with the potential to promote revascularization and tissue healing within poorly vascularized, non-healing wounds.

Properties of dehydrated human amnion/chorion composite grafts: Implications for wound repair and soft tissue regeneration

“…Histological staining of dHACM tissue sections demonstrated preservation of the layers of the amnion and chorion, including the processing of human amniotic membrane retains an array of cytokines, chemokines, and growth factors naturally present in the native tissue. Together with our previous analyses, 15,16 we have identified a diverse array of 57 regulatory proteins present in dHACM allografts. These proteins are known to regulate a variety of processes involved in inflammation, angiogenesis, ECM remodeling, and tissue regeneration (Table I).…”

“…We previously reported a number of biological activities of dHACM, including induction of proliferation of human dermal fibroblasts and microvascular endothelial cells, upregulation of angiogenic growth factors by endothelial cells, chemotactic recruitment of mesenchymal stem cells in vitro and in vivo, as well as increased neovascularization in a mouse subcutaneous implantation model. 15,16 Thus, dHACM contains an array of regulatory molecules that can positively influence processes critical for the three phases of wound repair: inflammation, angiogenesis, and production and remodeling of the ECM.…”

“…15,16 In this study, we report the presence and amount of an additional 36 signaling molecules, including 14 cytokines and 10 chemokines known to regulate inflammation, and 12 cytokines known to regulate wound healing processes (Table I).…”

“…13,14 A number of these, as well as additional growth factors, have also been previously identified in significant quantities in PURION V R processed dehydrated human amnion/chorion membrane (dHACM) tissues, including TGF-a, TGF-b1, bFGF, EGF, HGF, placental growth factor (PlGF), granulocyte colony-stimulating factor (GCSF), angiogenin, angiopoietin-2 (ANG-2), heparin binding epidermal growth factor (HB-EGF), platelet-derived growth factor-AA (PDGF-AA), PDGF-BB, and vascular endothelial growth factor (VEGF), along with other interleukins (ILs) and tissue inhibitors of metalloproteinases (TIMPs). 15,16 Despite the increasing use of amniotic membrane products in a clinical setting, the characterization of these tissue products remains fairly superficial, including identification of the vast array of growth factors present in these tissues, which likely contribute to the tissues' bioactivity and clinical efficacy. Therefore, the goal of these studies was to characterize PURION V R processed dHACM, including the effectiveness of the PURION V R process and the stability of the resulting products.…”

Evaluation of Dehydrated Human Amnion/Chorion Membrane as an Adhesion Barrier in Women Undergoing Robotic Laparoscopy

“…It has been suggested that decreased fibrinolytic activity induced by the cytokine TNF may impair the natural dissolution of fibrin deposits at the peritoneum in the presence of an inflammatory reaction [15]. Cell regulatory factors including TNF-α and IL-10 have been shown to be down regulated in the presence of dHACM [16].…”