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Promising biomaterials for facilitating regeneration should be tested in appropriate large animal models that better recapitulate human inflammatory and regenerative responses than rodent models. Previous studies have shown tyrosine-derived polycarbonates (TyrPC) are versatile biomaterials with a wide range of tissue engineering applications across multiple disciplines. The library of TyrPC has been well studied and consists of thousands of polymer compositions with tunable mechanical characteristics and degradation and resorption rates that are useful for the design of nerve guidance tubes (NGTs). NGTs made of different TyrPCs have been used in segmental nerve defect models in small animals. The current study is an extension of this work and evaluates the effects of NGTs made using two different TyrPC compositions in a porcine model of peripheral nerve injury and repair. We first evaluated a nondegradable TyrPC formulation in a 1 cm segmental nerve defect model in pigs, demonstrating proof-of-concept of chronic regenerative efficacy up to 6 months, at which time nerve/muscle electrophysiology and nerve morphometry were similar to those attained by an autograft repair control. Next, we characterized the acute regenerative response to a degradable TyrPC formulation using the same 1 cm segmental defect model. After 2 weeks in vivo , this TyrPC NGT was found to promote the deposition by host cells of pro-regenerative extracellular matrix (ECM) constituents (in particular collagen I, collagen III, collagen IV, laminin and fibronectin) at levels exceeding those deposited inside commercially available collagen-based NGTs. This corresponded with dense and rapid infiltration of host Schwann cells and axons into the lumen of the NGT and axonal crossing of the lesion into the distal nerve segment. These findings confirmed results reported previously in a mouse model and reveal that TyrPC NGTs were well tolerated in swine and facilitated host axon regeneration and Schwann cell infiltration in the acute phase across segmental defects - likely by eliciting a favorable neurotrophic ECM milieu. This regenerative response ultimately can contribute to functional recovery.

X-ray phase contrast imaging technique has been applied for the study of morphological variations in soft tissues. The effect of an antioxidant, α-lipoic acid in reducing hypercholesterolemia in rats is investigated. The experiment was conducted to measure serum lipid profile and diameter of vessels in rat liver, as liver is the most vital organ in hypolipidemic activity studies. Methods: Four groups of male Wistar rats, control (Group I), hyperlipidemic (Group II), positive control (Group III) and treated Group IV)) were studied for serum lipid profile and liver vessels with synchrotron X-ray phase tomography. The Group I rats received chow diet, in Group II rats, administration of 20% butter rich diet induced hyperlipidemia. Group III, treated rats received hypolipidemic drug Atorvastatin and Group IV animals received a potent antioxidant DL-α-Lipoic acid. The excised liver tissue immersed in 10% formalin. X-ray phase contrast tomography was performed for comparison of diameter of liver vessels. Results: Among the four group of animals, the diameter of liver vessels was much larger in hypercholesterolemic rat (Group II). The liver vessel diameter comparison with X-ray phase contrast tomography and the lipid profile shows reduction in serum lipids and lipoproteins by ALA treatment.