Skip to main content
2024 BMES Annual Meeting Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

Tissue Engineering

Tissue Engineering - Poster Session D

Poster BB12 - A biodegradable piezoelectric gelatin scaffold promotes axon growth for use in spinal cord repair

Friday, October 25, 2024
3:30 PM – 4:30 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Spinal cord injury (SCI) results in axonal damage and consequently, functional loss for which there is no effective treatment at the present time. Axon growth across the injured site is necessary for functional recovery, but endogenous axon growth is limited. Electrical cues have been shown to improve axon growth; however, the need for external electrodes is a significant drawback. Piezoelectric smart biomaterials are promising for spinal cord regeneration due to their self-powered capability of generating electrical stimulation to enhance axon growth. However, traditional piezoelectric biomaterials are either non-biodegradable or lack adequate mechanical properties. We address these limitations by introducing biodegradable, aligned gelatin scaffolds with tunable piezoelectric properties which is promising for enhancing axon growth. This study also aims to evaluate the potential of an aligned gelatin scaffold to alleviate the formation of glial scar. Astrocytes, the most abundant glial cell in the spinal cord, become reactive and play a critical role in inflammation and scar formation at the site of injury. The resulting scar tissue, composed of chondroitin sulfate proteoglycans (CSPGs) secreted by reactive astrocytes, acts as a chemical and physical barrier for axon growth, preventing sensory and motor recovery following SCI. Therefore, piezoelectric aligned gelatin scaffold promoting axon growth and reducing astrocyte reactivity will have a profound impact.

Materials and

Methods:  Gelatin (bovine skin) was electrospun in a rotating mandrel collector to form aligned fibrous mat and crosslinked to increase the hydrolytic stability. The fiber diameter and the alignment were evaluated using scanning electron microscopy (SEM). Scaffolds are poled with a high electric field to enhance their piezoelectric properties. The piezoelectric coefficient, d33 was evaluated for the following groups: positively poled (Poled (+)), negatively poled (Poled (-)), which are based on the direction of the applied electric field, and the unpoled scaffold serves as a control for piezoelectric properties. In vitro neurite growth studies are performed by growing rat embryonic day 17 (E17) dorsal root ganglion (DRG) explant on the groups for three days. Axon lengths from the DRG explants are evaluated by neurofilament (NF) staining and imaged with fluorescence microscopy. The 10 longest neurites were measured from each side of the DRG body (n=20 per DRG) using the freehand line tool in ImageJ software and the average neurite extension was calculated per scaffold. To establish a model for scar formation on the aligned fibers, astrocytes were maintained in serum-containing media to produce reactive phenotype modified using previously reported methods. {Yu, 2012 #35} After the culture became confluent, reactive astrocytes were switched to serum-free conditions and treated with 10 ng/ml TGF-β1. The reactive astrocytes and the control groups were stained for Glial Fibrillary Acidic protein (GFAP), CS-56 (CSPG side chain marker), and counterstained with Hoechst (nucleus). Statistical analysis was performed using one-way ANOVA with comparisons by Tukey’s post hoc test (p < 0.05).

Results, Conclusions, and Discussions: Using SEM, the fiber diameters of the electrospun aligned scaffolds were 647±88 nm and the degree of alignment was 83.4± 9.8%. We demonstrated a tunable piezoelectric property for poled gelatin scaffolds. The d33 measurements of Poled (+) scaffolds were 0.43±0.31 pC/N and Poled (-) scaffolds were -0.28±0.12 pC/N (Figure: 1). Average neurite extension from all groups demonstrated that the aligned gelatin scaffold is favorable for axon growth. Poled (-) group demonstrated the highest axon extension. A significant difference between Poled (+) and Poled (-) was observed for average neurite growth (Figure: 2). Upcoming studies will evaluate the performance of aligned gelatin scaffold for reducing astrocytic scar and reactivity in vitro. Therefore, reactive astrocytes were produced and characterized on tissue culture plastic (TCP) and compared with the control groups (Figure 3). In the next study, reactive astrocytes will be cultured in the aligned gelatin scaffolds and the presence of CSPG will be evaluated with CS-56 marker. We hope to see the minimal presence of CSPGs in the scaffolds, which will indicate that the aligned piezoelectric gelatin scaffolds can promote axon growth and reduce the glial scar, demonstrating the potential for functional recovery.

Acknowledgements (Optional):  Acknowledgements: We would like to thank support from NSF Science and Technology Center for Engineering Mechanobiology (CEMB)- #1548571.