title: The delayed addition of human mesenchymal stem cells to pre-formed endothelial cell networks results in functional vascularization of a collagen-glycosaminoglycan scaffold in vivo.
abstract: This paper demonstrates a method to engineer, in vitro, a nascent microvasculature within a collagen-glycosaminoglycan scaffold with a view to overcoming the major issue of graft failure due to avascular necrosis of tissue-engineered constructs. Human umbilical vein endothelial cells (ECs) were cultured alone and in various co-culture combinations with human mesenchymal stem cells (MSCs) to determine their vasculogenic abilities in vitro. Results demonstrated that the delayed addition of MSCs to pre-formed EC networks, whereby MSCs act as pericytes to the nascent vessels, resulted in the best developed vasculature. The results also demonstrate that the crosstalk between ECs and MSCs during microvessel formation occurs in a highly regulated, spatio-temporal fashion, whereby the initial seeding of ECs results in platelet derived growth factor (PDGF) release; the subsequent addition of MSCs 3 days later leads to a cessation in PDGF production, coinciding with increased vascular endothelial cell growth factor expression and enhanced vessel formation. Functional assessment of these pre-engineered constructs in a subcutaneous rat implant model demonstrated anastomosis between the in vitro engineered vessels and the host vasculature, with significantly increased vascularization occurring in the co-culture group. This study has thus provided new information on the process of in vitro vasculogenesis within a three-dimensional porous scaffold for tissue engineering and demonstrates the potential for using these vascularized scaffolds in the repair of critical sized bone defects.
authors: Tissue Engineering Research Group, Royal College of Surgeons in Ireland, Dublin, Ireland; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin, Ireland.
authors: T M
authors: TM
authors: McFadden
authors: G P
authors: GP
authors: Duffy
authors: A B
authors: AB
authors: Allen
authors: H Y
authors: HY
authors: Stevens
authors: S M
authors: SM
authors: Schwarzmaier
authors: N
authors: N
authors: Plesnila
authors: J M
authors: JM
authors: Murphy
authors: F P
authors: FP
authors: Barry
authors: R E
authors: RE
authors: Guldberg
authors: F J
authors: FJ
authors: O'Brien
mesh_terms: D000792:Angiography; D000818:Animals; D001808:Blood Vessels / Q000473:pathology; D002417:Cattle; D018920:Coculture Techniques; D003094:Collagen / Q000494:pharmacology*; D006025:Glycosaminoglycans / Q000494:pharmacology*; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology*; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D036641:Microscopy, Fluorescence, Multiphoton; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D051381:Rats; D013194:Staining and Labeling; D054457:Tissue Scaffolds / Q000737:chemistry*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D055114:X-Ray Microtomography
chemical_list: D006025:Glycosaminoglycans; D010982:Platelet-Derived Growth Factor; D042461:Vascular Endothelial Growth Factor A; D003094:Collagen
keywords: Co-culture; Collagen–GAG scaffold; Endothelial cells; In vivo vascularization; Mesenchymal stem cells