Human mesenchymal stem cell implantation and collagen modification as a tool for tissue engineering

Abstract

Tissue engineering, in all its aspects, is a focus of increasing interest. Optimum vascularization has to be ensured ahead of transferring experimental designs to clinical applications. Our group searched for matrix modifications and cell sources liable to increase vessel formation in engineered tissue. Notwithstanding the ethical issues, adult human mesenchymal stem cells (hMSC) seemed to offer as unlimited a possibility of proliferation and differentiation as embryonic stem cells. These series of experiments focused on the differentiation capability of adult stem cells and organisation in modified collagen sponges. Adult mesenchymal stem cells were cultured to the second generation. Two different groups were formed: Group A cells remained in medium without additional growth factors. Group B cells were cultured in angiogenic differentiation medium. On day 21, the cells of both groups were detached and implanted into different collagen sponges: unmodified collagen sponges and EDC/NHS [1-ethyl-3(3-dimethyl-aminopropyl) carbodiimide (EDC) and N-hydroxysuccinmide (NHS)] cross-linked and heparinized collagen scaffolds. Twenty-one days later, the sponges were prepared for the histological evaluation. After 3 weeks in culture, the cells of group B showed phenotypic endothelial cell characteristics and expressed von-Willebrand factor. Enhanced proliferation and invasion on cross-linked and heparinised matrices were obtained with both cell types (A and B). In addition, the stem cell derived endothelial cells formed organised structures throughout the scaffolds. Obtained data revealed the differentiation capability of adult MSC into endothelial cells and organisation in modified collagen matrices. This approach might lead to optimised vascular incorporation in tissue replacement.