Objectives: To evaluate: (i) the neuro-regenerative potential of chitosan membrane (CS-Me) on acutely axotomised autonomic neurones in vitro; (ii) to exclude the possibility that a pro-regenerative biomaterial could interfere with the proliferation activity of prostate cancer cell lines; (iii) to provide an in vivo proof of the biocompatibility and regeneration promoting effect of CS-Me in a standardised rat model of peripheral nerve injury and repair; (iv) finally, to evaluate the tissue reaction induced by the degrading material; as previous studies have shown promising effects of CS-Me for protection of the neurovascular bundles for potency recovery in patients that undergo nerve-sparing radical prostatectomy (RP).
Materials and methods: Addressing aim (i), the neuro-regenerative potential, organotypic cultures derived from primary sympathetic ganglia were cultured on CS-Me over 3 days and neurite extension and axonal sprouting were evaluated. Addressing aim (ii), effects of CS on cancer cells, different human prostate cancer cell lines (PC3, DU-145, LN-Cap) were seeded on CS-coated plates or cultured in the presence of CS-Me dissolution products. Addressing aims (iii) and (iv), functional recovery of peripheral nerve fibres and tissue reaction with the biomaterial, CS-Me and CS nerve guides were used to repair a median nerve injury in the rat. Functional recovery was evaluated during the post-recovery time by the behavioural grasping test.
Results: CS-Me significantly stimulated axon elongation from autonomic ganglia in comparison to control conditions in organotypic three-dimensional cultures. CS coating, as well as the dissolution products of CS-Me, led to a significantly lower proliferation rate of prostate cancer cell lines in vitro. Tissue reaction towards CS-Me and standard CS nerve guides was similar in the rat median nerve model, as was the outcome of nerve fibre regeneration and functional recovery.
Conclusion: The results of this study provide the first experimental evidence in support of the clinical safety of CS-Me and of their postulated effectiveness for improving functional recovery after RP. The presented results are coherent in demonstrating that acutely axotomised autonomic neurones show increased neurite outgrowth on CS-Me substrate, whilst the same substrate reduces prostate cancer cell line proliferation in vitro. Furthermore, CS-Me do not demonstrate any disadvantage for peripheral nerve repair in a standard animal model.
Keywords: autonomic ganglia; chitosan; nerve regeneration; prostate cancer.
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