pH-Sensitive Chitosan Hydrogel with Instant Gelation for Myocardial Regeneration

Recently in situ injectable hydrogels have received considerable attention to regenerate failure heart tissue after myocardial infarction (MI). But two criteria remain crucial: first, defining their chemical composition and structural parameters because they must be fabricated to withstand physiological condition while having high cell retention; second, providing the hydrogel with short gelation time to protect the cells from washout and extrusion in the injection site. In this study, two different pH-sensitive hydrogels with instant gelation in the presence of aqueous acetic acid (WH sample), and DMEM medium along with acetic acid (MH sample) were prepared. The morphology and structural and mechanical properties of the hydrogels were evaluated by SEM, FTIR and compressive strength test, respectively. Also, the equilibrium swelling ratio of each hydrogel and their degradation rate as a desirable property were also determined. MTT test confirmed that both hydrogels were biocompatible and non-toxic for human Bone Marrow Mesenchymal Stem Cells (hBMSCs) within 14 days as well as 31 and 36% cell growth during this time for WH and MH samples, respectively. The viability investigation of human Adipose Mesenchymal Stem Cells (hADSCs), tested by live/dead assay with Acridine Orange and Ethidium bromide staining, showed high cell survival and cell density increase during 1, 7, 14, 21 days. The overall results demonstrated that both in situ forming hydrogels are promising candidates for regeneration of the infarcted myocardium.