Preliminary Study On Chitosan/Silk Blend Hydrogels And Its Application As Bone Marrow Mesenchymal Stem Cells Culture Scaffold

As the biomaterial within a three-dimensional network structure, the polymer hydrogel having higher porosity and stronger water retaintion and similar to the mechanical properties of adipose tissue, is one of the most likely materials used as scaffolds for adipose tissue engineering. In this study, the chitosan/silk blend hydrogels were prepared in a relatively short time through blending chitosan with silk and induced by β-glycerophosphate. The cellular affinity of silk could improve cell adhesion and grow of chitosan hydrogels. The influences of chitosan/silk ratio of the hydrogels on the pore structure and viscoelasticity and compressive strength were studied. Bone marrow mesenchymal stem cells(BMSCs) were isolated from SD rat. The biological characteristics of BMSCs were affirmed via the identification by CD34 and CD90 and BMSCs differentiated into adipocyte by the induction of dexamethasone. The influences of chitodan/silk blend hydrogels on cell adhesion and growth were preliminary studied after BMSCs were inoculated in chitosan/silk blend hydrogels and cultured in vitro.Firstly, different ratio of chitosan/silk blend hydrogels were prepared and the influences on gelation time, pore structure, viscoelasticity and compressive strength of the hydrogels were studied. The results showed that the chitosan/silk blend hydrogels could be prepared in a relatively short time by blending chitosan with silk fibroin induced by β-glycerophosphate. The gelation time were 15 min and 25 min as the proportion of chitosan/silk blend solution 75/25 and 50/50, respectively. At chitosan/silk blend proportion of 75/25, 50/50 and 25/75, the average pore diameter of the blend hydrogels were 96.58 um,118.26 um and 132.67 um, respectively. The blend hydrogels have larger pore diameter at the larger silk proportion. The compression and rheological test results indicated that the chitosan/silk blend hydrogels have the mechanical property of elastic material and the blend proportion of 75/25 have a lager compressive strength than others.Secondly, BMSCs were identified by CD34 and CD90 and differentiated into adipocyte. The identified results revealed that BMSCs were isolated from SD rat successfully by the method of this paper. The cells grow circinately with homogeneous cellular morphology and tight cell arrangement. The BMSCs fusion degree reached 80-90% after 6-7d. The oil red O tests showed that BMSCs could differentiate into adipocyte by the induction of dexamethasone.Finally, the influences of chitodan/silk blend hydrogels on cell adhesion and grow were studied initiatively as BMSCs were inoculated in the hydrogels observed by LSCM and SEM. The results showed that, compared with pure chitosan hydrogels, the BMSCs cultured in the chitosan/silk blend hydrogels of 75/25 and 50/50 have stronger survival property and higher rate of growth and spread of cell pseudopodia, and it also could secrete extracellular matrices. The results indicated that the microenvironment of cell adhesion and growth were improved by adding silk to prepared chitosan/silk blend hydrogels.