An immunohistochemical analysis of the temporal and spatial expression of growth factors FGF 1, 2 and 18, IGF 1 and 2, and TGFbeta1 during distraction osteogenesis

Reconstruction of massive tibial defect caused by osteomyelitis using induced membrane followed by trifocal bone transport technique: a retrospective study and our experience

OBJECTIVE

To evaluate clinical outcomes of the application of induced membrane followed by trifocal bone transport technique in the treatment of massive tibial defect caused by osteomyelitis.

METHOD

A total of 18 eligible patients with tibial defect > 6 cm caused by osteomyelitis who were admitted to our institution from January 2010 to January 2016 and treated by induced membrane followed by trifocal bone transport technique. There were 12 male and 6 females with an average age of 40.4 years old. A detailed demographic data (age, sex, etiology, previous operation time, defect size and location, interval from Masquelet technique to trifocal bone transport technique, external fixation index (EFI), duration of regenerate consolidation and docking union) were collected, bone and functional outcomes were evaluated by Association for the Study and Application of the Method of Ilizarov (ASAMI) scoring system. Complications during and in the period of follow up were recorded and evaluated by Paley classification at a minimum follow-up of 2 years.

RESULTS

The etiology include posttraumatic osteomyelitis in 13 cases and primary osteomyelitis in 5 cases. An average of previous operation time was 3.4 times. Mean tibial defect after radical debridement was 6.8 cm. An average interval duration from formation of induced membrane to trifocal bone transport was 4.8 weeks. An average of EFI was 37.1 days/cm, the duration of regenerate consolidation and docking union were 124.7 days and 186.4 days, respectively. An average time of follow-up after removal of external fixator was 28.5 month without recurrence of osteomyelitis. The bony outcome was excellent in 6 cases, good in 8 cases, fair in 3 cases and poor in 1 case, and functional outcome was excellent in 4 cases, good in 10 cases, fair in 2 cases and poor in 2 cases. The most common complication was pin tract infection which occurred in 15 cases and there were no major complications such as nerve or vascular injury.

CONCLUSION

Massive tibial defect caused by osteomyelitis can be successfully treated first stage using induced membrane followed by second stage using trifocal bone transport technique, which is an effective method in terms of radical elimination of osteomyelitis with expected clinical outcomes.

Bone Microvasculature: Stimulus for Tissue Function and Regeneration

Bone is a highly vascularized organ, providing structural support to the body, and its development, regeneration, and remodeling depend on the microvascular homeostasis. Loss or impairment of vascular function can develop diseases, such as large bone defects, avascular necrosis, osteoporosis, osteoarthritis, and osteopetrosis. In this review, we summarize how vasculature controls bone development and homeostasis in normal and disease cases. A better understanding of this process will facilitate the development of novel disease treatments that promote bone regeneration and remodeling. Specifically, approaches based on tissue engineering components, such as stem cells and growth factors, have demonstrated the capacity to induce bone microvasculature regeneration and mineralization. This knowledge will have relevant clinical implications for the treatment of bone disorders by developing novel pharmaceutical approaches and bone grafts. Finally, the tissue engineering approaches incorporating vascular components may widely be applied to treat other organ diseases by enhancing their regeneration capacity. Impact statement Bone vasculature is imperative in the process of bone development, regeneration, and remodeling. Alterations or disruption of the bone vasculature leads to loss of bone homeostasis and the development of bone diseases. In this study, we review the role of vasculature on bone diseases and how vascular tissue engineering strategies, with a detailed emphasis on the role of stem cells and growth factors, will contribute to bone therapeutics.

[Research progress of tibial transverse transport for diabetic foot]

Objective

To summarize the research progress of tibial transverse transport in the treatment of diabetic foot.

Methods

The domestic and foreign literature on the tibial transverse transport for diabetic foot in recent years was summarized, and the advantages and disadvantages of the technique were analyzed.

Results

The tibial transverse transport was an innovation based on Ilizarov technique. At present, the treatment of diabetic foot by the tibial transverse transport is in the initial stage and has achieved good results, but there are also problems such as ulcer recurrence and re-fracture. And its biological mechanism to promote tissue regeneration, clinical technical points (such as the selection of incision and bone window size), the technical parameters of postoperative removal program, and the postoperative effectiveness are still in dispute and exploration. More clinical studies and practices are needed in the future to develop a standard protocol for this technique.

Conclusion

Tibial transverse transport is a hot spot for microcirculation reconstruction of lower extremity. Significant progress has been made in the treatment of diabetic foot, which provides a new direction for limb salvage treatment. However, the technique is not mature, there are still many disputes and difficulties to be further studied clearly.

Enhanced tendon-bone healing with acidic fibroblast growth factor delivered in collagen in a rabbit anterior cruciate ligament reconstruction model

Background

The objective of the present study was to investigate the effectiveness of acidic fibroblast growth factor delivered in collagen (aFGF/collagen) for promoting tendon–bone interface healing after anterior cruciate ligament (ACL) reconstruction in rabbits.

Methods

ACL reconstructions were performed in the right hind limbs of New Zealand rabbits. Each left long digital extensor tendon was harvested as an autograft, and collagen incorporating different concentrations of aFGF or same amount of collagen alone was applied at the tendon–bone interface after ACL reconstruction. The control group underwent ACL reconstruction only. There were high and low aFGF/collagen groups, collagen alone group, and control group (n = 21 rabbits per group). Histological and biomechanical analyses were performed at 4, 8, and 12 weeks postoperatively to evaluate the effect of aFGF/collagen on tendon–bone interface healing.

Results

Results of biomechanical tests showed that at both 8 and 12 weeks postoperatively, the elastic modulus and stiffness in both the high and low aFGF/collagen treatment groups were significantly higher than those in the control group and collagen alone group, with that in the high aFGF/collagen concentration group being the highest. Histological analysis showed that at 8 weeks, tightly organized Sharpey-like fibers were observed in both aFGF/collagen groups with new bone growth into the tendon in the high concentration group. At 12 weeks postoperatively, a fibrocartilage transition zone was observed in the bone tunnels in both aFGF/collagen groups, especially in the high aFGF/collagen group.

Conclusion

Application of the aFGF/collagen composite could enhance early healing at the tendon–bone interface after ACL reconstruction, especially with the use of a high aFGF/collagen concentration.

Bone grafts and biomaterials substitutes for bone defect repair: A review

Bone grafts have been predominated used to treat bone defects, delayed union or non-union, and spinal fusion in orthopaedic clinically for a period of time, despite the emergency of synthetic bone graft substitutes. Nevertheless, the integration of allogeneic grafts and synthetic substitutes with host bone was found jeopardized in long-term follow-up studies. Hence, the enhancement of osteointegration of these grafts and substitutes with host bone is considerably important. To address this problem, addition of various growth factors, such as bone morphogenetic proteins (BMPs), parathyroid hormone (PTH) and platelet rich plasma (PRP), into structural allografts and synthetic substitutes have been considered. Although clinical applications of these factors have exhibited good bone formation, their further application was limited due to high cost and potential adverse side effects. Alternatively, bioinorganic ions such as magnesium, strontium and zinc are considered as alternative of osteogenic biological factors. Hence, this paper aims to review the currently available bone grafts and bone substitutes as well as the biological and bio-inorganic factors for the treatments of bone defect.

Acceleration of Fracture Healing by Overexpression of Basic Fibroblast Growth Factor in the Mesenchymal Stromal Cells

In this study, we engineered mesenchymal stem cells (MSCs) to over‐express basic fibroblast growth factor (bFGF) and evaluated its effects on fracture healing. Adipose‐derived mouse MSCs were transduced to express bFGF and green fluorescence protein (ADSC^bFGF‐GFP). Closed‐femoral fractures were performed with osterix‐mCherry reporter mice of both sexes. The mice received 3 × 10⁵ ADSCs transfected with control vector or bFGF via intramuscular injection within or around the fracture sites. Mice were euthanized at days 7, 14, and 35 to monitor MSC engraftment, osteogenic differentiation, callus formation, and bone strength. Compared to ADSC culture alone, ADSC^bFGF increased bFGF expression and higher levels of bFGF and vascular endothelial growth factor (VEGF) in the culture supernatant for up to 14 days. ADSC^bFGF treatment increased GFP‐labeled MSCs at the fracture gaps and these cells were incorporated into the newly formed callus. quantitative reverse transcription polymerase chain reaction (qRT‐PCR) from the callus revealed a 2‐ to 12‐fold increase in the expression of genes associated with nervous system regeneration, angiogenesis, and matrix formation. Compared to the control, ADSC^bFGF treatment increased VEGF expression at the periosteal region of the callus, remodeling of collagen into mineralized callus and bone strength. In summary, MSC^bFGF accelerated fracture healing by increasing the production of growth factors that stimulated angiogenesis and differentiation of MSCs to osteoblasts that formed new bone and accelerated fracture repair. This novel treatment may reduce the time required for fracture healing. Stem Cells Translational Medicine2017;6:1880–1893

MiR-503 Promotes Bone Formation in Distraction Osteogenesis through Suppressing Smurf1 Expression

Distraction osteogenesis (DO) is a unique technique for promoting bone formation in clinical practice. However the underlying mechanism remains elusive. As epigenetic mediators, microRNAs have been reported to play important roles in regulating osteogenesis. In this study, after successfully established the DO model of rats, a microRNA microarray was performed to find molecular targets for DO. Total 100 microRNAs were identified as differently expressed, with miR-503 being one of the most significantly up-regulated miRNAs in DO. The further investigation also showed that miR-503 was upregulated during osteogenesis in mesenchymal stem cells of rats, and overexpression of miR-503 significantly promoted osteogenesis in vitro and accelerated mineralization in DO process in vivo. By using bioinformatic investigations and luciferase activities, we successfully demonstrated that Smurf1, a negative regulator of osteogenesis, was a real target of miR-503. Furthermore, Smurf1 knockdown promoted osteogenesis and antagomir-503 abolished the promotive effect, suggesting that miR-503 mediated osteogenic differentiation via suppressing Smurf1 expression. To sum up, these findings indicated that miR-503 promoted osteogenesis and accelerated bone formation, which may shed light on the development for a potential therapeutic target for bone repair.

Comprehensive Review of Adipose Stem Cells and Their Implication in Distraction Osteogenesis and Bone Regeneration

Bone is one of the most dynamic tissues in the human body that can heal following injury without leaving a scar. However, in instances of extensive bone loss, this intrinsic capacity of bone to heal may not be sufficient and external intervention becomes necessary. Several techniques are available to address this problem, including autogenous bone grafts and allografts. However, all these techniques have their own limitations. An alternative method is the technique of distraction osteogenesis, where gradual and controlled distraction of two bony segments after osteotomy leads to induction of new bone formation. Although distraction osteogenesis usually gives satisfactory results, its major limitation is the prolonged duration of time required before the external fixator is removed, which may lead to numerous complications. Numerous methods to accelerate bone formation in the context of distraction osteogenesis have been reported. A viable alternative to autogenous bone grafts for a source of osteogenic cells is mesenchymal stem cells from bone marrow. However, there are certain problems with bone marrow aspirate. Hence, scientists have investigated other sources for mesenchymal stem cells, specifically adipose tissue, which has been shown to be an excellent source of mesenchymal stem cells. In this paper, the potential use of adipose stem cells to stimulate bone formation is discussed.

Bone marrow aspirate concentrate and platelet-rich plasma enhanced bone healing in distraction osteogenesis of the tibia

BACKGROUND

During lower limb lengthening, poor bone regeneration is a devastating complication. Several local or systemic applications have been used to promote osteogenesis, and biologic stimulations are gaining attention, but their utility has not been proven in this setting.

QUESTIONS/PURPOSES

In patients undergoing bilateral tibial lengthening, we compared those receiving an osteotomy site injection of autologous bone marrow aspirate concentrate (BMAC) plus platelet-rich plasma (PRP) with those not receiving such an injection in terms of external fixator index (time in external fixation divided by amount of lengthening), full weightbearing index (time until a patient was permitted to do full weightbearing divided by amount of lengthening), four cortical healing indexes (time until each cortical union divided by amount of lengthening), and callus shape and type.

METHODS

Twenty-two patients (44 tibias) undergoing bilateral tibial lengthening enrolled in this randomized trial. Two patients were excluded, one due to insufficient radiographic evaluation and one who was lost to followup, leaving 20 patients (40 segments) for inclusion. Ten patients (20 segments) received BMAC combined with PRP injection (treatment group) and 10 patients (20 segments) received no injection (control group). All patients underwent stature lengthening for familial short stature with the lengthening over nail technique. Autologous BMAC combined with PRP was injected at the tibial osteotomy site at the end of the index surgery. Mean distraction rates were similar between groups (0.75 mm/day in the treatment group versus 0.72 mm/day in the control group; p = 0.24). Full weightbearing was permitted when we observed radiographic evidence of healing at two cortices; this assessment was made by the surgeon who was blinded to the treatment each patient received. Minimum followup was 24 months (mean, 28 months; range, 24-34 months).

RESULTS

There was no difference in mean external fixator index between groups. However, mean cortical healing indexes (anterior/posterior/medial/lateral) were 1.14/0.81/0.96/0.88 months/cm in the treatment group and 1.47/1.26/1.42/1.22 months/cm in the control group (all p < 0.001), showing faster healing in the treatment group at each cortex. Full weightbearing was permitted earlier in the treatment group than in the control group (index: 0.99 months/cm and 1.38 months/cm, respectively, p < 0.001). Callus shape and type were not different between groups.

CONCLUSIONS

Autologous BMAC combined with PRP injection at the osteotomy site helped improve bone healing in distraction osteogenesis of the tibia, although the effect size was small.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

The effect of altering the mechanical loading environment on the expression of bone regenerating molecules in cases of distraction osteogenesis

Distraction osteogenesis (DO) is a surgical technique where gradual and controlled separation of two bony fragments following an osteotomy leads to the induction of new bone formation in the distracted gap. DO is used for limb lengthening, correction of bony deformities, and the replacement of bone loss secondary to infection, trauma, and tumors. Although DO gives satisfactory results in most cases, one major drawback of this technique is the prolonged period of time the external fixator has to be kept on until the newly formed bone consolidates thus leading to numerous complications. Numerous attempts at accelerating bone formation during DO have been reported. One specific approach is manipulation of the mechanical environment during DO by applying changes in the standard protocol of distraction. Attempts at changing this mechanical environment led to mixed results. Increasing the rate or applying acute distraction, led to poor bone formation in the distracted zone. On the other hand, the addition of compressive forces (such as weight bearing, alternating distraction with compression or by over-lengthening, and then shortening) has been reported to increase bone formation. It still remains unclear why these alterations may lead to changes in bone formation. While the cellular and molecular changes occurring during the standard DO protocol, specifically increased expression of transforming growth factor-β1, platelet-derived growth factor, insulin-like growth factor, basic fibroblast growth factor, vascular endothelial growth factor, and bone morphogenic proteins have been extensively investigated, the literature is sparse on the changes occurring when this protocol is altered. It is the purpose of this article to review the pertinent literature on the changes in the expression of various proteins and molecules as a result of changes in the mechanical loading technique in DO and try to define potential future research directions.

The effect of heparan sulfate application on bone formation during distraction osteogenesis

Bone morphogenetic proteins (BMPs) are recognized for their ability to induce bone formation in vivo and in vitro. Their osteogenic and osteoinductive properties are tightly regulated by the secretion of specific BMP antagonists, which have been shown to physically bind and sometimes be blocked by the extracellular proteoglycan heparan sulphate side chains (from hereon referred to as HS). The purpose of this study was to investigate if local application of 5 µg of HS proteoglycan to a bone regenerate site in a mouse model of distraction osteogenesis (DO) can accelerate bone healing and affect the expression of key members of the BMP signaling pathway. DO was performed on the right tibia of 115 adult male wild-type mice. At mid-distraction (day 11), half the group was injected locally with 5 µg of HS, while the other half was injected with saline. The mice were sacrificed at 2 time-points: mid-consolidation (34 days) and full consolidation (51 days). The distracted tibial zone was then collected for analysis by μCT, radiology, biomechanical testing, immunohistochemistry, and histology. While μCT data showed no statistically significant difference in bone formation, the results of biomechanical testing in stiffness and ultimate force were significantly lower in the HS-injected bones at 51 days, compared to controls. Immunohistochemistry results also suggested a decrease in expression of several key members of the BMP signaling pathway at 34 days. Furthermore, wound dehiscence and infection rates were significantly elevated in the HS group compared to the controls, which resulted in a higher rate of euthanasia in the treatment group. Our findings demonstrate that exogenous application of 5 µg of HS in the distracted gap of a murine model had a negative impact on bone and wound healing.

Spatial and temporal localization of WNT signaling proteins in a mouse model of distraction osteogenesis

While the surgical procedure of distraction osteogenesis (DO) is very successful in the treatment of orthopedic conditions, its major limitation of slow bone formation in the distracted gap has prompted numerous attempts to understand and accelerate this slow bone formation. Interestingly, WNT/FZD signaling has been identified as a critical pathway in mediating bone formation and regeneration but has not yet been studied in the context of DO. The objective of this study was to determine the spatial and temporal localization of endogenous WNT signaling proteins at various times of bone formation in a wild-type mouse model of DO. In this study, the DO protocol performed on mice consisted of three phases: latency (5 days), distraction (12 days), and consolidation (34 days). Our immunohistochemical findings of distracted bone specimens show an increased expression of WNT ligands (WNT4 and WNT10A), receptors (FZD1 and 2, LRP5 and 6), β-catenin, and pathway antagonizers (DKK1; CTBP1 and 2; sFRP1, 2, and 4) during the distraction phase, which were then down-regulated during consolidation. This is the first published report to show an activation of the WNT pathway in DO and could help identify WNT as a potential therapeutic target in accelerating bone regeneration during DO.

Fibroblast growth factor expression during skeletal fracture healing in mice

Fibroblast growth factors (FGFs) are important signaling molecules that regulate many stages of endochondral bone development. During the healing of a skeletal fracture, several features of endochondral bone development are reactivated. To better understand the role of FGFs in skeletal fracture healing, we quantitatively evaluated the temporal expression patterns of Fgfs, Fgf receptors (Fgfrs), and molecular markers of bone development over a 14-day period following long bone fracture in a mouse model. These studies identify distinct groups of FGFs that are differentially expressed and suggest active stage-specific roles for FGF signaling during the fracture repair process.