Siddharth Nimbalkar

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Extracellular matrix mimetic hydrogels which hybridize synthetic and natural polymers offer molecularly-tailored, bioactive properties and tunable mechanical strength. In addition, 3D bioprinting by stereolithography allows fabrication of internal pores and defined macroscopic shapes. In this study, we formulated a hybrid biocompatible resin using natural and synthetic polymers (chitosan and polyethylene glycol diacrylate (PEGDA), respectively) by controlling molecular weight of chitosan, feed-ratios, and photo-initiator concentration. Ear-shaped, hybrid scaffolds were fabricated by a stereolithographic method using a 405 nm laser. Hybrid hydrogel scaffolds of chitosan (50-190 kDa) and PEGDA (575 Da) were mixed at varying feed-ratios. Some of the cationic, amino groups of chitosan were neutralized by dialysis in acidic solution containing chitosan in excess of sodium acetate solution to inhibit quenching of newly formed photoradicals. A feed-ratio of 1:7.5 was found to be the most a...

Loss of the neuromuscular junction (NMJ) is an early and critical hallmark in all forms of amyotrophic lateral sclerosis (ALS). Herein, a functional NMJ disease model is developed by integrating motoneurons (MNs) differentiated from multiple ALS‐patients’ induced pluripotent stem cells (iPSCs) and primary human muscle into a chambered system. NMJ functionality is tested by recording myotube contractions while stimulating MNs by field electrodes and a set of clinically relevant parameters is defined to characterize the NMJ function. Three ALS lines are analyzed, two with SOD1 mutations and one with an FUS mutation. The ALS‐MNs reproduce pathological phenotypes, including increased axonal varicosities, reduced axonal branching and elongation, and increased excitability. These MNs form functional NMJs with wild type muscle, but with significant deficits in NMJ quantity, fidelity, and fatigue index. Furthermore, treatment with the Deanna protocol is found to correct the NMJ deficits in all the ALS mutant lines tested. Quantitative analysis also reveals the variations inherent in each mutant line. This functional NMJ system provides a platform for the study of both fALS and sALS and has the capability of being adapted into subtype‐specific or patient‐specific models for ALS etiological investigation and patient stratification for drug testing.

Dr Xiufang Guo1, Dr Virginia Smith1, Max Jackson2, My Tran1, Michael Thomas1, Aakash Patel1, Eric Lorusso1, Siddharth Nimbalkar1, Yunqing Cai1, Dr Christopher McAleer2, Ying Wang3, Dr Christopher Long2, Dr James Hickman1,2 1NanoScience Technology Center, University Of Central Florida, Orlando, United States, 2Hesperos, Inc., Orlando, United States, 3Department of Biomedical Engineering, Cornell University, Orlando, United States