Repeated penile girth enhancement with biodegradable scaffolds： microscopic ultrastructural analysis and surgical benefits

Autologous tissue engineering using biodegradable scaffolds as a carrier is a well-known procedure for penile girth enhancement. We evaluated a group of previously treated patients with the aim to analyze histomorphometric changes after tissue remodeling and to estimate the benefits of repeated procedure. Between February 2012 and December 2016, a group of 21 patients, aged 22-37 （mean 28.0） years, underwent a repeated penile girth enhancement procedure with biodegradable scaffolds. Procedure included insertion of two poly-lactic-co-glycolic acid scaffolds seeded with laboratory-prepared fibroblasts from scrotal tissue specimens. During this procedure, biopsy specimens of tissue formed after the first surgery were taken for microscopic analysis. The mean follow-up was 38 months. Connective tissue with an abundance of connective tissue fibers, small blood vessels, and inflammatory cells were observed in all analyzed surgically removed tissue. Ultrastructural analysis of these tissue samples discovered the presence of large quantities of collagen fibrils running parallel to each other, forming bundles, with a few widely spread fibroblasts. In total, the mean values of flaccid and erect gain in girth after the second surgery were 1.1 ± 0.4 （range： 0.6- 1.7） cm and 1.0±0.3 （range： 0.6-1.5） cm, respectively. Microscopic evaluation of newly formed tissue, induced by autologous tissue engineering using biodegradable scaffolds, showed the presence of vascularized loose connective tissue with an abundance of collagen fibers, fibroblasts, and inflammatory cells, indicating active neovascularization and fibrinogenesis. The benefit of the repeated enhancement procedure was statistically significant.

Polyethylene glycol as a promising synthetic material for repair of spinal cord injury

Polyethylene glycol is a synthetic, biodegradable, and water-soluble polyether. Owing to its good biological and material properties, polyethylene glycol shows promise in spinal cord tissue engineering applications. Although studies have examined repairing spinal cord injury with polyethylene glycol, these compelling findings have not been recently reviewed or evaluated as a whole. Thus, we herein review and summarize the findings of studies conducted both within and beyond China that have examined the repair of spinal cord injury using polyethylene glycol. The following summarizes the results of studies using polyethylene glycol alone as well as coupled with polymers or hydrogels：（1） polyethylene glycol as an adjustable biomolecule carrier resists nerve fiber degeneration, reduces the inflammatory response, inhibits vacuole and scar formation, and protects nerve membranes in the acute stage of spinal cord injury.（2） Polyethylene glycol-coupled polymers not only promote angiogenesis but also carry drugs or bioactive molecules to the injury site. Because such polymers cross both the blood-spinal cord and blood-brain barriers, they have been widely used as drug carriers.（3） Polyethylene glycol hydrogels have been used as supporting substrates for the growth of stem cells after injury, inducing cell migration, proliferation, and differentiation. Simultaneously, polyethylene glycol hydrogels isolate or reduce local glial scar invasion, promote and guide axonal regeneration, cross the transplanted area, and re-establish synaptic connections with target tissue, thereby promoting spinal cord repair. On the basis of the reviewed studies, we conclude that polyethylene glycol is a promising synthetic material for use in the repair of spinal cord injury.

Novel hybrid biocomposites for tendon grafts:The addition of silk to polydioxanone and poly(lactide-co-caprolactone)enhances material properties,in vitro and in vivo biocompatibility

Biopolymers play a critical role as scaffolds used in tendon and ligament(TL)regeneration.Although advanced biopolymer materials have been proposed with optimised mechanical properties,biocompatibility,degradation,and processability,it is still challenging to find the right balance between these properties.Here,we aim to develop novel hybrid biocomposites based on poly(p-dioxanone)(PDO),poly(lactide-co-caprolactone)(LCL)and silk to produce high-performance grafts suitable for TL tissue repair.Biocomposites containing 1-15%of silk were studied through a range of characterisation techniques.We then explored biocompatibility through in vitro and in vivo studies using a mouse model.We found that adding up to 5%silk increases the tensile properties,degradation rate and miscibility between PDO and LCL phases without agglomeration of silk inside the composites.Furthermore,addition of silk increases surface roughness and hydrophilicity.In vitro experiments show that the silk improved attachment of tendon-derived stem cells and proliferation over 72 h,while in vivo studies indicate that the silk can reduce the expression of pro-inflammatory cytokines after six weeks of implantation.Finally,we selected a promising biocomposite and created a prototype TL graft based on extruded fibres.We found that the tensile properties of both individual fibres and braided grafts could be suitable for anterior cruciate ligament(ACL)repair applications.