Effect of vacuum-assisted closure combined with open bone grafting to promote rabbit bone graft vascularization

An Elastic Mineralized 3D Electrospun PCL Nanofibrous Scaffold for Drug Release and Bone Tissue Engineering

Complex shaped and critical-sized bone defects have been a clinical challenge for many years. Scaffold-based strategies such as hydrogels provide localized drug release while filling complex defect shapes, but ultimately possess weaknesses in low mechanical strength alongside a lack of macroporous and collagen-mimicking nanofibrous structures. Thus, there is a demand for mechanically strong, extracellular matrix (ECM) mimicking scaffolds that can robustly fit complex shaped critical sized defects and simultaneously provide localized, sustained, multiple growth factor release. We therefore developed a composite, bi-phasic PCL/hydroxyapatite (HA) 3D nanofibrous (NF) scaffold for bone tissue regeneration by using our innovative electrospun-based thermally induced self-agglomeration (TISA) technique. One intriguing feature of our ECM-mimicking TISA scaffolds is that they are highly elastic and porous even after evenly coated with minerals and can easily be pressed to fit different defect shapes. Furthermore, the bio-mimetic mineral deposition technique allowed us to simultaneously encapsulate different type of drugs, e.g., proteins and small molecules, on TISA scaffolds under physiologically mild conditions. Compared to scaffolds with physically surface-adsorbed phenamil, a BMP2 signaling agonist, incorporated phenamil composite scaffolds indicated less burst release and longer lasting sustained release of phenamil with subsequently improved osteogenic differentiation of cells in vitro. Overall, our study indicated that the innovative press-fit 3D NF composite scaffold may be a robust tool for multiple-drug delivery and bone tissue engineering.

Reconstruction of massive tibial bone and soft tissue defects by trifocal bone transport combined with soft tissue distraction: experience from 31 cases

BACKGROUND

Large post-traumatic tibial bone defects combined with soft tissue defects are a common orthopedic clinical problem associated with poor outcomes when treated using traditional surgical methods. The study was designed to investigate the safety and efficacy of trifocal bone transport (TFT) and soft-tissue transport with the Ilizarov technique for large posttraumatic tibial bone and soft tissue defects.

METHODS

We retrospectively reviewed 31 patients with massive posttraumatic tibial bone and soft tissue defects from May 2009 to May 2016. All of the eligible patients were managed by TFT and soft-tissue transport. The median age was 33.4 years (range, 2-58 years). The mean defect of bone was 11.87 cm ± 2.78 cm (range, 8.2-18.2 cm) after radical resection performed by TFT. The soft tissue defects ranged from 7 cm × 8 cm to 24 cm × 12 cm. The observed results included bone union time, wound close time and true complications. The Association for the Study and Application of the Method of Ilizarov (ASAMI) scoring system was used to assess bone and functional results and postoperative complications were evaluated by Paley classification.

RESULTS

The mean duration of follow-up after frame removal was 32 months (range, 12-96 months). All cases achieved complete union in both the elongation sites and the docking sites, and eradication of infection. The mean bone transport time was 94.04 ± 23.33 days (range, 63.7-147 days). The mean external fixation time was 22.74 ± 6.82 months (range, 14-37 months), and the mean external fixation index (EFI) was 1.91 ± 0.3 months/cm (range, 1.2-2.5 months/cm). The bone results were excellent in 6 patients, good in 14 patients, fair in 8 patients and poor in 3 patients. The functional results were excellent in 8 patients, good in 15 patients, fair in 5 patients and poor in 3 patients.

CONCLUSION

TFT, in conjunction with soft tissue transport technique, can give good results in most patients (in this article, good and excellent results were observed in 64% of patients). Soft tissue transport is a feasible method in providing good soft tissue coverage on the bone ends. Although it has no advantages over microvascular techniques, it might be an good alternative in the absence of an experienced flap surgeon. Nonetheless, high-quality controlled studies are needed to assess its long-term safety and efficacy.

Studies of Superb Microvascular Imaging and Contrast-Enhanced Ultrasonography in the Evaluation of Vascularization in Early Bone Regeneration

OBJECTIVE

The aim of this study was to investigate value of superb microvascular imaging (SMI) and contrast-enhanced ultrasonography (CEUS) in evaluating the neovascularization of early bone regeneration.

METHODS

Twenty-five Sprague-Dawley male rats were implanted with recombinant human bone morphogenetic protein-2/calcium phosphate cement (rhBMP-2/) in the muscle space of the left hind limb near the femoral head to establish the rat model of intramuscular ectopic osteogenesis. Ultrasonography and pathologic analysis were performed on the 3rd, 7th, 14th, 21st, and 28th days after modeling. Two-dimensional ultrasonography, SMI, and CEUS were used to assess neovascularization and bone formation.

RESULTS

Pathologic examination showed that different levels of neovascularization were observed in the graft bone over time after modeling, which increased significantly from the 3rd to 14th day, and then gradually decreased. CEUS and SMI showed no obvious microvessels inside the graft bone on the 3rd day. On the 7th day after modeling, a small number of neovascular vessels were observed around the graft bone. On the 14th day, neovascularization was observed in both the peripheral and inner parts of the graft bone. The number of neovascular vessels inside the graft bone had decreased gradually by the 21st and 28th days. The results of SMI and CEUS indexes showed that the vascular index, peak intensity, enhancement intensity, and enhancement rate first increased and then decreased with time. Their peak points were found on the 14th day. Arrival time, time to peak, and enhancement time decreased gradually over time (P < .05).

CONCLUSION

The combined application of SMI and CEUS may be useful in evaluating the neovascularization of early osteoanagenesis.

MicroRNA-98-5p prevents bone regeneration by targeting high mobility group AT-Hook 2

MicroRNAs (mRNAs or miRs) serve an important role in the regulation of gene expression. In the present study, the role of miR-98-5p in bone regeneration was determined. Three osteoblast cell models were established, including primary human stem cells (BMMSC), mouse BMMSC's and MC3T3-E1 cells. miR-98-5p expression was determined using reverse transcription-quantitative (RT-q)PCR. Osteoblast markers, including alkaline phosphatase, runt related transcription factor 2 and transcription factor Sp7, were determined using RT-qPCR and western blot analysis, respectively. Alkaline phosphatase activity was determined in the present study and cell proliferation and apoptosis assays were performed. Furthermore, an association between miR-98-5p and high mobility group AT-Hook 2 (HMGA2) was revealed. This association was determined using TargetScan and a dual luciferase reporter assay. The current study demonstrated that miR-98-5p was downregulated during osteogenic differentiation and further demonstrated that HMGA2 may be a direct target of miR-98-5p. The results also demonstrated that miR-98-5p upregulation significantly inhibited the osteogenic differentiation of MC3T3-E1 cells, an effect that was reversed by an increased HMGA2 expression. Additionally, the results revealed that miR-98-5p upregulation inhibited MC3T3-E1 cell viability and induced cell apoptosis and these effects were eliminated by HMGA2 overexpression. In conclusion, miR-98-5p may prevent bone regeneration through inhibiting osteogenic differentiation and osteoblast growth by targeting HMGA2.

EWMA Document: Negative Pressure Wound Therapy

1. Introduction Since its introduction in clinical practice in the early 1990's negative pressure wounds therapy (NPWT) has become widely used in the management of complex wounds in both inpatient and outpatient care.¹ NPWT has been described as a effective treatment for wounds of many different aetiologies^2,3 and suggested as a gold standard for treatment of wounds such as open abdominal wounds,^4-6 dehisced sternal wounds following cardiac surgery^7,8 and as a valuable agent in complex non-healing wounds.^9,10 Increasingly, NPWT is being applied in the primary and home-care setting, where it is described as having the potential to improve the efficacy of wound management and help reduce the reliance on hospital-based care.¹¹ While the potential of NPWT is promising and the clinical use of the treatment is widespread, highlevel evidence of its effectiveness and economic benefits remain sparse.^12-14 The ongoing controversy regarding high-level evidence in wound care in general is well known. There is a consensus that clinical practice should be evidence-based, which can be difficult to achieve due to confusion about the value of the various approaches to wound management; however, we have to rely on the best available evidence. The need to review wound strategies and treatments in order to reduce the burden of care in an efficient way is urgent. If patients at risk of delayed wound healing are identified earlier and aggressive interventions are taken before the wound deteriorates and complications occur, both patient morbidity and health-care costs can be significantly reduced. There is further a fundamental confusion over the best way to evaluate the effectiveness of interventions in this complex patient population. This is illustrated by reviews of the value of various treatment strategies for non-healing wounds, which have highlighted methodological inconsistencies in primary research. This situation is confounded by differences in the advice given by regulatory and reimbursement bodies in various countries regarding both study design and the ways in which results are interpreted. In response to this confusion, the European Wound Management Association (EWMA) has been publishing a number of interdisciplinary documents^15-19 with the intention of highlighting: The nature and extent of the problem for wound management: from the clinical perspective as well as that of care givers and the patients Evidence-based practice as an integration of clinical expertise with the best available clinical evidence from systematic research The nature and extent of the problem for wound management: from the policy maker and healthcare system perspectives The controversy regarding the value of various approaches to wound management and care is illustrated by the case of NPWT, synonymous with topical negative pressure or vacuum therapy and cited as branded VAC (vacuum-assisted closure) therapy. This is a mode of therapy used to encourage wound healing. It is used as a primary treatment of chronic wounds, in complex acute wounds and as an adjunct for temporary closure and wound bed preparation preceding surgical procedures such as skin grafts and flap surgery. Aim An increasing number of papers on the effect of NPWT are being published. However, due to the low evidence level the treatment remains controversial from the policy maker and health-care system's points of view-particularly with regard to evidence-based medicine. In response EWMA has established an interdisciplinary working group to describe the present knowledge with regard to NPWT and provide overview of its implications for organisation of care, documentation, communication, patient safety, and health economic aspects. These goals will be achieved by the following: Present the rational and scientific support for each delivered statement Uncover controversies and issues related to the use of NPWT in wound management Implications of implementing NPWT as a treatment strategy in the health-care system Provide information and offer perspectives of NPWT from the viewpoints of health-care staff, policy makers, politicians, industry, patients and hospital administrators who are indirectly or directly involved in wound management.

MicroRNA-495 Inhibits New Bone Regeneration via Targeting High Mobility Group AT-Hook 2 (HMGA2)

Background

MicroRNAs play critical roles in post-translational gene expression. In this study, we explored the role of miR-495 in new bone regeneration.

Material/Methods

Murine calvarial osteoblasts were isolated and cultured. Microarray was performed to identify differential miRNAs in medicarpin-induced osteoblasts differentiation. Luciferase reporter assay was performed to identify the target gene of miRNA. Murine osteoblast cells were transfected with miC, miR-495, or anti-miR-495. CCK-8 and flow cytometry were performed to detect osteoblasts proliferation and apoptosis. Western blot was used to analyze apoptosis-related proteins. qRT-PCR analysis was performed to detect gene expression. ALP activity and mineralized nodule formation test were used to evaluate bone formation. Dill-hole injury model was constructed and micro CT was utilized to measuring bone healing.

Results

Microarray analysis identified miR-495 as our miRNA of interest and luciferase reporter assay identified HMGA2 as its target gene. Over-expression of miR-495 significantly inhibited ALP activity and mineralized nodule formation as well as the expression of RUNX-2, BMP-2, and Osterix. Also, miR-495 over-expression inhibited osteoblasts proliferation and promoted apoptosis obviously. In this in vivo study, the downregulation of miR-495 promoted murine femur healing.

Conclusions

MiR-495 inhibits new bone regeneration via targeting high mobility group AT-Hook 2 (HMGA2). We propose that targeting miR-495 may be a promising therapeutic approach for bone regeneration.