Gelatin-methacrylamide gel loaded with microspheres to deliver GDNF in bilayer collagen conduit promoting sciatic nerve growth

Abstract

In this study, we fabricated glial cell-line derived neurotrophic factor (GDNF)-loaded microspheres, then seeded the microspheres in gelatin-methacrylamide hydrogel, which was finally integrated with the commercial bilayer collagen membrane (Bio-Gide ® ). The novel composite of nerve conduit was employed to bridge a 10 mm long sciatic nerve defect in a rat. GDNF-loaded gelatin microspheres had a smooth surface with an average diameter of 3.9±1.8 μm. Scanning electron microscopy showed that microspheres were uniformly distributed in both the GelMA gel and the layered structure. Using enzyme-linked immunosorbent assay, in vitro release studies (pH 7.4) of GDNF from microspheres exhibited an initial burst release during the first 3 days (18.0%±1.3%), and then, a prolonged-release profile extended to 32 days. However, in an acidic condition (pH 2.5), the initial release percentage of GDNF was up to 91.2%±0.9% within 4 hours and the cumulative release percentage of GDNF was 99.2%±0.2% at 48 hours. Then the composite conduct was implanted in a 10 mm critical defect gap of sciatic nerve in a rat. We found that the nerve was regenerated in both conduit and autograft (AG) groups. A combination of electrophysiological assessment and histomorphometry analysis of regenerated nerves showed that axonal regeneration and functional recovery in collagen tube filled with GDNF-loaded microspheres (GM + CT) group were similar to AG group ( P >0.05). Most myelinated nerves were matured and arranged densely with a uniform structure of myelin in a neat pattern along the long axis in the AG and GM + CT groups, however, regenerated nerve was absent in the BLANK group, left the 10 mm gap empty after resection, and the nerve fiber exhibited a disordered arrangement in the collagen tube group. These results indicated that the hybrid system of bilayer collagen conduit and GDNF-loaded gelatin microspheres combined with gelatin-methacrylamide hydrogels could serve as a new biodegradable artificial nerve guide for nerve tissue engineering.

Biodegradable Bisvinyl Sulfonemethyl-crosslinked Gelatin Conduit Promotes Regeneration after Peripheral Nerve Injury in Adult Rats

“… These results indicate that the hybrid conduit can serve as a new artificial graft. 46 Elastin Glutaraldehyde 10 The nerves were matured after 10 weeks in the conduit groups. The study suggests that functional elastin can be used as a biomaterial for peripheral nerve regeneration.…”

How to Build and to Protect the Neuromuscular Junction: The Role of the Glial Cell Line-Derived Neurotrophic Factor

“…From there, it can be retrogradely transported to the soma of MNs as demonstrated by an in vitro model of the compartmentalized microfluidic neuromuscular co-culture system [ 43 ]. It also participates in NMJ formation and maintenance and its ability to induce neurite sprouting in axonal injury models has been clearly demonstrated [ 44 , 45 ]. Indeed, after spinal cord injury (SCI), GDNF is upregulated specifically in Schwann cells for weeks, making them important as potential points of intervention for SCI therapies [ 46 , 47 ].…”

Recent trends in gelatin methacryloyl nanocomposite hydrogels for tissue engineering

“…46 However, cell encapsulation is not possible while crosslinking with aldehydes as they elicit cytotoxic, immunogenic, and inflammatory responses. Subsequently, chemicals such as acyl azides 47 and 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) 48 have been used to crosslink gelatin to reduce the risk of cytotoxicity. Apart from these, a natural and biodegradable molecule, genipin, has also been used to generate non-toxic cell-laden hydrogels.…”