Injectable hydrogel for antioxidant therapy and cell encapsulation

Abstract

Event Abstract Back to Event Injectable hydrogel for antioxidant therapy and cell encapsulation Remya Komeri1* and Jayabalan Muthu1* 1 Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, India Introduction: The myocardial infarction associated with ischemia ends up in cardiac rupture. The free radicals released from necrotic cadiomyocytes are one of the reasons limiting cell engraftment on cardiomyoplasty. The conventional antioxidant therapy with vitamin C, E and beta carotene are dose responsive with slight changes in oral intake causing toxicity[1]. Recently injectable hydrogels are employed to scavenge the radicals. Pullulan hydrogel[2], silk protein[3] and chitosan-gelatin-glycerol phosphate hydrogel[4] are reported with radical scavenging property. The reported hydrogels are derived from the natural polymers having insufficient mechanical stability for cardiac applications. Here we have designed an in situ gelling, injectable, mechanically stable, free radical scavenging hydrogel for cardiomyoblast cell encapsulation and delivery. Methods: The hydrogel, PEAM was prepared using a comacromer synthesized with 1.5 M dihydroxy poly ethylene adipate, 1.5 M D-Mannitol, 1.5 M poly ethylene glycol 300 and 3 M maleic anhydride by condensation at 180 0C for 1 h (Fig.1A). The injectable formulation was prepared by crosslinking the comacromer with 0.1 g/ml PEGDiacrylate, 5 μl of 0.4 M APS and 1 μl of 6M TEMED. . The swelling value, surface porosity (ESEM), free water content (DSC) and variation of stiffness of hydrogel before and after aging in physiological media were determined. The DPPH radical scavenging property, superoxide anion scavenging activity and total reducing power of hydrogel were determined. The cytocompatibility of hydrogel extract was analysed by MTT assay. The recovery of cardiomyoblasts from oxidative stress in the presence of hydrogel was analyzed by MTT and live dead assay. The encapsulation efficiency of hydrogel was studied with H9c2 cells. Fig. 1. Results and Discussion: The DSC analysis reveals 30.93% bound water due to abundant hydrophilic groups (Fig.1B). The present hydrogel is mechanically favourable by retaining Young’s modulus,181 kPa within that of native myocardium[5] after 30 days of aging (Fig. 1C). The ESEM of hydrogel reveal smaller surface pores (Fig.1D.a) and larger bulk pores (Fig.1D.b) favorable for cell retention. The free radical scavenging ability [DPPH radical scavenging (53%), superoxide scavenging (86%) and total reducing power (161%)] of hydrogel is comparable with ascorbic acid. The hydrogel is capable of protecting cells from oxidative stress comparable with ascorbic acid (Fig. 2. MTT assay (A) & live dead assay of H9c2 cells (B,Control cells (B.a), H2O2 control (B.b), PEAM hydrogel treated (B.c) and ascorbic acid treated (B.d)] ). The PEAM hydrogel is cytocompatible and maintains viability of encapsulated cells for longer duration [Live dead assay (Fig. 2Ca) and H&E staining of cell encapsulated hydrogel (Fig 2C.b) after 30 days]. The encapsulated cells have also proliferated inside the hydrogel [MTT assay(Fig.2D)]. Fig. 2. Conclusion: The present PEAM cytocompatible and bioresorbable hydrogel is a potential candidate for cell encapsulation and antioxidant therapy.