Pluripotent stem cell chondrogenesis in hydrogels/scaffolds

Abstract

Articular cartilage injury from trauma or diseases is a serious problem for people of all ages. Due to the limited natural healing capacity of cartilage and the drawbacks of current treatments, new repair technologies including tissue engineering approaches have been developed to deal with these problems. Pluripotent stem cells have been suggested as a very attractive source for tissue engineering application because of their pluripotency and self-renewal properties. Therefore, the objective of this thesis was to generate functional chondrocytes from human embryonic stem cells (hESCs) and to create in vitro three-dimensional (3D) cartilage constructs using those hESC-derived chondrogenic cells for cartilage repair. In this study, I first modified the published 14-day chondrogenesis protocol to generate chondrocytes from hESCs in two-dimensional (2D) culture. The application of small molecules (ROCK inhibitor or ascorbic acid-2-phosphate), substrate stiffness and low-intensity pulsed ultrasound (LIPUS) to the protocol was investigated in order to improve the efficiency of the chondrogenic protocol. Results showed that the use of all those applications to the protocol did not substantially affect chondrogenesis from hESCs. Therefore, conditions for using those applications may need to be optimized further to give improvement in chondrogenesis. Next, I explored several types of hydrogels/scaffolds i.e. fibrin gels, peptide gels, collagen membranes, hyaluronan gels, hyaluronic acid (HA)-modified fibrin gels, dextran-tyramine/hyaluronan-tyramine (Dex-TA/HA-TA) hydrogels for 3D culture of hESC-derived chondrogenic cells to generate 3D tissue-engineered cartilage. The responses of cells, in terms of cell viability, morphology and the expression of chondrocyte-associated genes, i.e. SOX9, COL2 and ACAN, in those hydrogels/scaffolds were investigated. Results revealed that among those hydrogels/scaffolds, only Dex-TA/HA-TA hydrogels showed a trend to promote chondrogenesis of hESC-derived chondrogenic cells in 3D culture, indicated by higher viability and expression of chondrogenic-associated genes in comparison with starting chondrogenic cells. However, further biological investigations of this hydrogel need to be performed to verify its chondrogenic potential. This finding suggests that Dex-TA/HA-TA hydrogels may be a promising hydrogel for cartilage tissue engineering application. In order to achieve more efficient cartilage repair, they could be modified using several strategies to improve their biological and mechanical properties.

Date of Award	1 Aug 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Susan Kimber (Supervisor) & Christoph Ballestrem (Supervisor)