Chondrogenic Differentiation Potential of Human Adipose Stem Cell Spheroid Forming on Glycol Chitosan and Gelatin Hydrogel

Cartilage tissue often suffers from difficulties to repair after injury due to a lack of blood vessel and neural systems. Furthermore, since cartilage tissues serve as buffers between bones and are often located at joints, irreversible injury or dysfunction of the whole joint might occur if the damage is not repaired in time. As a result, repairing cartilage tissue has long been an essential topic in tissue engineering.

Human adipose derived stem cells (hASCs) are proved to have the potential to differentiate into different lineage including adipogenic, osteogenic and chondrogenic lineage. They are considered to be the cell sources in cartilage tissue engineering.

Glycol chitosan, which is recently studied for cartilage repairing due to its similar structures to glycosaminoglycans found in cartilage and the decent biocompatibility and degradability in vivo. In this study, hydrogel mixed with glycol chitosan and gelatine is used as a carrier of hASCs and abilities for the cells to adhere, proliferate and differentiate on the hydrogel composite are evaluated, in order to analyse the potential of chodrongenic differentiation of glycol chitosan.

The existence of gelatine can enhance the cell adhesion ability of the composite, however, as gelatine is released out of the composite with time, hASCs will start to form a spheroid structure. The formation of spheroids was attributed to the releasing of gelatine and the characteristic of glycol chitosan, which the surface of glycol chitosan will induce the formation of cell spheroids, in which researches have indicated that cell spheroids can stimulate the differentiate ability.

These spheroids were observed by fluorescence and SEM to test their properties and gene expression of differentiation. Further stimulation using chodrongenic differentiation medium to trigger the spheroids to differentiate was conducted, the results showed chondrogenic differentiation performance appeared in cell spheroids. Moreover, the spheroids formed with the induction medium were larger and had more complete shape of sphere. They also had higher performance in chondrogenic differentiation.