Hallmarks of peripheral nerve function in bone regeneration

Skeletal tissue is highly innervated.Although different types of nerves have been recently identified in the bone,the crosstalk between bone and nerves remains unclear.In this review,we outline the role of the peripheral nervous system(PNS)in bone regeneration following injury.We first introduce the conserved role of nerves in tissue regeneration in species ranging from amphibians to mammals.We then present the distribution of the PNS in the skeletal system under physiological conditions,fractures,or regeneration.Furthermore,we summarize the ways in which the PNS communicates with bone-lineage cells,the vasculature,and immune cells in the bone microenvironment.Based on this comprehensive and timely review,we conclude that the PNS regulates bone regeneration through neuropeptides or neurotransmitters and cells in the peripheral nerves.An in-depth understanding of the roles of peripheral nerves in bone regeneration will inform the development of new strategies based on bone-nerve crosstalk in promoting bone repair and regeneration.

Multifunctional hydrogel enhances bone regeneration through sustained release of Stromal Cell-Derived Factor-1αand exosomes

Fracture nonunion remains a great challenge for orthopedic surgeons.Fracture repair comprises of three phases,the inflammatory,repair and remodeling stage.Extensive advancements have been made in the field of bone repair,including development of strategies to balance the M1/M2 macrophage populations,and to improve osteogenesis and angiogenesis.However,such developments focused on only one or the latter two phases,while ignoring the inflammatory phase during which cell recruitment occurs.In this study,we combined Stromal Cell-Derived Factor-1α(SDF-1α)and M2 macrophage derived exosomes(M2D-Exos)with a hyaluronic acid(HA)-based hydrogel precursor solution to synthesize an injectable,self-healing,adhesive HA@SDF-1α/M2D-Exos hydrogel.The HA hydrogel demonstrated good biocompatibility and hemostatic ability,with the 4%HA hydrogels displaying great antibacterial activity against gram-negative E.coli and gram-positive S.aureus and Methicillin-resistant Staphylococcus aureus(MRSA).Synchronously and sustainably released SDF-1αand M2D-Exos from the HA@SDF-1α/M2D-Exos hydrogel enhanced proliferation and migration of human bone marrow mesenchymal stem cell(HMSCs)and Human Umbilical Vein Endothelial Cells(HUVECs),promoting osteogenesis and angiogenesis both in vivo and in vitro.Overall,the developed HA@SDF-1α/M2D-Exos hydrogel was compatible with the natural healing process of fractures and provides a new modality for accelerating bone repair by coupling osteogenesis,angiogenesis,and resisting infection at all stages.

Methods used for evaluation of volume retention rate in autologous fat grafting for breast augmentation: a systematic review

Background:Autologous fat grafting has gained popularity in breast augmentation.Various methods can be used to estimate the volume retention rate.This systematic review aimed to establish whether the type of method used for measuring breast volume is a factor that influences the reported volume retention rate.Methods:Studies were identified using the electronic databases PubMed,Embase,Cochrane Central Register of Controlled Trials,and Web of Science from inception of the database up to February 2019.Articles describing autologous fat grafting for breast augmentation were selected based on pre-determined inclusion and exclusion criteria.The characteristics of the included studies were summarized,and the reported volume retention rate from the studies was compared.A quality assessment of all included articles was performed using the methodological index for non-randomized studies criteria.Results:A total of 618 articles were identified,of which 12 studies,with a total of 1337 cases,were eligible.The retention rate of injected adipose tissue varied when the method of fat grafting and volume analysis used were both the same,as well as when the method of fat grafting was the same but the method of volumetric evaluation used was different.Conclusions:Currently,the tools available for estimating the volume retention rate come with limitations.In order to objectively evaluate the percentage of graft retention,a standard protocol that applies to the different methods should be established in the future.

Advances and perspective on animal models and hydrogel biomaterials for diabetic wound healing

Diabetic wounds are a common complication in diabetes patients.Due to peripheral nerve damage and vascular dysfunction,diabetic wounds are prone to progress to local ulcers,wound gangrene and even to require amputation,bringing huge psychological and economic burdens to patients.However,the current treatment methods for diabetic wounds mainly include wound accessories,negative pressure drainage,skin grafting and surgery;there is still no ideal treatment to promote diabetic wound healing at present.Appropriate animal models can simulate the physiological mechanism of diabetic wounds,providing a basis for translational research in treating diabetic wound healing.Although there are no animal models that can fully mimic the pathophysiological mechanisms of diabetic wounds in humans,it is vital to explore animal simulation models used in basic research and preclinical studies of diabetic wounds.In addition,hydrogel materials are regarded as a promising treatment for diabetic wounds because of their good antimicrobial activity,biocompatibility,biodegradation and appropriate mechanical properties.Herein,we review and discuss the different animal models used to investigate the pathological mechanisms of diabetic wounds.We further discuss the promising future application of hydrogel biomaterials in diabetic wound healing.