Advances in the surface modification techniques of bone-related implants for last 10 years

At the time of implanting bone-related implants into human body,a variety of biological responses to the material surface occur with respect to surface chemistry and physical state.The commonly used biomaterials(e.g.titanium and its alloy,Co–Cr alloy,stainless steel,polyetheretherketone,ultra-high molecular weight polyethylene and various calcium phosphates)have many drawbacks such as lack of biocompatibility and improper mechanical properties.As surface modification is very promising technology to overcome such problems,a variety of surface modification techniques have been being investigated.This review paper covers recent advances in surface modification techniques of bone-related materials including physicochemical coating,radiation grafting,plasma surface engineering,ion beam processing and surface patterning techniques.The contents are organized with different types of techniques to applicable materials,and typical examples are also described.

Circular RNAs:typical biomarkers for bone-related diseases

Bone is a connective tissue that has important functions in the human body.Cells and the extracellular matrix(ECM)are key components of bone and are closely related to bone-related diseases.However,the outcomes of conventional treatments for bone-related diseases are not promising,and hence it is necessary to elucidate the exact regulatory mechanisms of bone-related diseases and identify novel biomarkers for diagnosis and therapy.Circular RNAs(circRNAs)are single-stranded RNAs that form closed circular structures without a 5’cap or 3’tail and polycyclic adenylate tails.Due to their high stability,circRNAs have the potential to be typical biomarkers.Accumulating evidence suggests that circRNAs are involved in bone-related diseases,including osteoarthritis,osteoporosis,osteosarcoma,multiple myeloma,intervertebral disc degeneration,and rheumatoid arthritis.Herein,we summarize the recent research progress on the characteristics and functions of circRNAs,and highlight the regulatory mechanism of circRNAs in bone-related diseases.

Vascularization and osteogenesis in ectopically implanted bone tissue-engineered constructs with endothelial and osteogenic differentiated adipose-derived stem cells

BACKGROUND A major problem in the healing of bone defects is insufficient or absent blood supply within the defect.To overcome this challenging problem,a plethora of approaches within bone tissue engineering have been developed recently.Bearing in mind that the interplay of various diffusible factors released by endothelial cells(ECs)and osteoblasts(OBs)have a pivotal role in bone growth and regeneration and that adjacent ECs and OBs also communicate directly through gap junctions,we set the focus on the simultaneous application of these cell types together with platelet-rich plasma(PRP)as a growth factor reservoir within ectopic bone tissue engineering constructs.AIM To vascularize and examine osteogenesis in bone tissue engineering constructs enriched with PRP and adipose-derived stem cells(ASCs)induced into ECs and OBs.METHODS ASCs isolated from adipose tissue,induced in vitro into ECs,OBs or just expanded were used for implant construction as followed:BPEO,endothelial and osteogenic differentiated ASCs with PRP and bone mineral matrix;BPUI,uninduced ASCs with PRP and bone mineral matrix;BC(control),only bone mineral matrix.At 1,2,4 and 8 wk after subcutaneous implantation in mice,implants were extracted and endothelial-related and bone-related gene expression were analyzed,while histological analyses were performed after 2 and 8 wk.RESULTS The percentage of vascularization was significantly higher in BC compared to BPUI and BPEO constructs 2 and 8 wk after implantation.BC had the lowest endothelial-related gene expression,weaker osteocalcin immunoexpression and Spp1 expression compared to BPUI and BPEO.Endothelial-related gene expression and osteocalcin immunoexpression were higher in BPUI compared to BC and BPEO.BPEO had a higher percentage of vascularization compared to BPUI and the highest CD31 immunoexpression among examined constructs.Except Vwf,endothelial-related gene expression in BPEO had a later onset and was upregulated and well-balanced during in vivo incubation that induced late onset of Spp1 expression and pronounced osteocalcin immunoexpression at 2 and 8 wk.Tissue regression was noticed in BPEO constructs after 8 wk.CONCLUSION Ectopically implanted BPEO constructs had a favorable impact on vascularization and osteogenesis,but tissue regression imposed the need for discovering a more optimal EC/OB ratio prior to considerations for clinical applications.

Nanomaterial-assisted theranosis of bone diseases

Bone-related diseases refer to a group of skeletal disorders that are characterized by bone and cartilage destruction.Conventional approaches can regulate bone homeostasis to a certain extent.However,these therapies are still associated with some undesirable problems.Fortunately,recent advances in nanomaterials have provided unprecedented opportunities for diagnosis and therapy of bone-related diseases.This review provides a comprehensive and up-to-date overview of current advanced theranostic nanomaterials in bone-related diseases.First,the potential utility of nanomaterials for biological imaging and biomarker detection is illustrated.Second,nanomaterials serve as therapeutic delivery platforms with special functions for bone homeostasis regulation and cellular modulation are highlighted.Finally,perspectives in this field are offered,including current key bottlenecks and future directions,which may be helpful for exploiting nanomaterials with novel properties and unique functions.This review will provide scientific guidance to enhance the development of advanced nanomaterials for the diagnosis and therapy of bone-related diseases.