Transplantation of culture expanded bone marrow cells and platelet rich plasma in distraction osteogenesis of the long bones

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

High-mobility group box 1 accelerates distraction osteogenesis healing via the recruitment of endogenous stem/progenitor cells

BACKGROUND AIMS

While distraction osteogenesis (DO) achieves substantial bone regeneration, prolonged fixation may lead to infections. Existing stem cell and physical therapies have limitations, requiring the development of novel therapeutic approaches. Here, we evaluated high-mobility group box 1 (HMGB1) as a novel therapeutic target for DO treatment.

METHODS

Micro-computed tomography (Micro-CT) analysis and histological staining of samples obtained from tibial DO model mice was performed. Transwell migration, wound healing, and proliferation assays were also performed on cultured human mesenchymal stem cells (hMSCs) and human umbilival vein endothelial cells (HUVECs). Tube formation assay was performed on HUVECs, whereas osteogenic differentiation assay was performed on hMSCs.

RESULTS

Micro-CT analysis and histological staining of mouse samples revealed that HMGB1 promotes bone regeneration during DO via the recruitment of PDGFRα and Sca-1 positve (PαS⁺) cells and endothelial progenitor cells. Furthermore, HMGB1 accelerated angiogenesis during DO, promoted the migration and osteogenic differentiation of hMSCs as well as the proliferation, migration and angiogenesis of HUVECs in vitro.

CONCLUSIONS

Our findings suggest that HMGB1 has a positive influence on endogenous stem/progenitor cells, representing a novel therapeutic target for the acceleration of DO-driven bone regeneration.

Concentrated Bone Marrow Aspirate Is More Cellular and Proliferative When Harvested From the Posterior Superior Iliac Spine Than the Proximal Humerus

PURPOSE

The purpose of this study is to determine whether concentrated bone marrow aspirate (cBMA) from the posterior superior iliac spine (PSIS) or proximal humerus (PH) produces a more productive cellular harvest in patients undergoing arthroscopic rotator cuff repair.

METHODS

Patients under 80 years old undergoing surgery for arthroscopic rotator cuff repair were enrolled. Two 60 mL aliquots of BMA were harvested from each subject, one from the PSIS and one from the PH. Each aliquot was processed independently to create cBMA. Cellular composition was determined using an automated hemocytometer and proliferative potential was studied with colony forming unit (CFU) assays.

RESULTS

Twelve patients were recruited (7 male, 5 female). The average age was 64.3 years (range 46.1-77.25 years) with body mass index of 26.8 (range 20.0-34.3). The average total nucleated cells (TNC) from PH was 18.7 × 10⁶ cells/mL (95% confidence interval [CI], 4.4-33.0; standard deviation [SD], 24.8) with 3.9 CFU/mL (95% CI, 0.3-7.5, SD, 5.7). The average TNC count from the PSIS was 55.9 × 10⁶ cells/mL (95% CI, 25.3-86.4; SD, 52.9) with 32.5 CFU/mL (95% CI, 11.5-53.5; SD, 33.1). The PSIS had a 3.0 times greater total nucleated cell yield (P = .014) and 8.3 times greater number of CFU/mL (P = .024) when compared to the PH. The average harvest time from the PSIS was 5.6 minutes and from the PH was 11.0 minutes (P = .043); harvest time did not account for additional time to prep and drape the PSIS.

CONCLUSIONS

The cBMA harvested from the PSIS resulted in a 3.0 times greater cellular yield and an 8.3 times greater proliferative product than cBMA from the PH.

CLINICAL RELEVANCE

When a more cellular cBMA product is sought to augment rotator cuff tear repair surgery, the PSIS is the preferred site for harvest.

Overexpressed osteoactivin reduced osteoclastic callus resorption during distraction osteogenesis in mice

Distraction osteogenesis is a widely used surgical technique to treat bone deformity and shortening. Several biological treatments have been studied to enhance bone formation during distraction osteogenesis in animals. However, role of osteoactivin in the osseous tissues during distraction osteogenesis remains poorly understood. In this animal experimental study, we investigated the spatiotemporal expression of osteoactivin by immunohistochemistry and real-time PCR using a mouse model for tibial lengthening. Furthermore, to address the role of osteoactivin in bone lengthening, we subjected the osteoactivin-transgenic mice to distraction osteogenesis model. During the lag phase, the fibroblast-like cells (possible progenitors of the osteoblasts or chondrocytes), which mainly express osteoactivin, were infiltrated into the osteotomy site. Osteoactivin was ubiquitously expressed in the lengthened segment during the distraction and consolidation phases. Consistent with the immunohistochemical analysis, the levels of the osteoactivin transcripts in the tibias were significantly increased throughout the distraction osteogenesis process. The bone mineral content in the osteoactivin-transgenic mice calculated using peripheral quantitative computed tomography was also significantly increased at the remodeling zone. The histomorphometric analysis revealed that newly formed callus resorption in the remodeling zone was significantly reduced but bone formation was not altered in the osteoactivin-transgenic mice. We conclude that osteoactivin functions as an inhibitor of callus resorption during the consolidation phase of distraction osteogenesis.

Can bone marrow aspirate improve mandibular fracture repair in camels (Camelus dromedarius)? A preliminary study

Background

Mandibular fractures are common in camels, leading to considerable economic losses. This study explored methods of improving mandibular fractures repair, adjuvant with interdental wire, or bone plate fixation. Autologous bone marrow (BM) injection enhances osteogenesis and rapid healing.

Objectives

To investigate the effect of autologous BM aspirate as an adjuvant treatment for repairing mandibular fractures in camels with interdental wire, or bone plate fixation.

Methods

Thirty dromedary camels aged 5–8 years and of both sexes were randomly divided into 4 treatment groups: group 1 (n = 10) treated with stainless steel wire fixation and BM injection at the fracture line, group 2 (n = 10) treated with plate fixation and BM injection at the fracture line, group 3 (n = 5) treated with stainless steel bone wire fixation and placebo saline injection at the fracture line, and group 4 (n = 5) treated with plate fixation and placebo injection at the fracture line. The mandibular fractures were followed weekly for 12 weeks postoperatively to assess improvement and healing based on clinical evaluation, radiographic union scale, and bone turnover markers (i.e., bone alkaline phosphatase, osteocalcin, pyridinoline, and deoxypyridinoline).

Results

Compared to other groups, elevated bone turnover markers in group 1 were demonstrated (p < 0.05) on the seventh postoperative day. Likewise, compared to other groups, both clinical findings and radiographic union scale significantly improved (p < 0.05) in group 1 on the 56th postoperative day.

Conclusions

BM aspirate has a promising beneficial osteogenic effect on mandibular fracture repair in camels, most notably when combined with interdental wire fixation.

Review of physical stimulation techniques for assisting distraction osteogenesis in maxillofacial reconstruction applications

Distraction Osteogenesis (DO) is an emerging limb lengthening method for the reconstruction of the hard tissue and the surrounding soft tissue, in different human body zones. DO plays an important role in treating bone defects in Maxillofacial Reconstruction Applications (MRA) due to reduced side effects and better formed bone tissue compared to conventional reconstruction methods i.e. autologous bone graft, and alloplast implantation. Recently, varying techniques have been evaluated to enhance the characteristics of the newly formed tissues and process parameters. Promising results have been shown in assisting DO treatments while benefiting bone formation mechanisms by using physical stimulation techniques, including photonic, electromagnetic, electrical, and mechanical stimulation technique. Using assisted DO techniques has provided superior results in the outcome of the DO procedure compared to a standard DO procedure. However, DO methods, as well as assisting technologies applied during the DO procedure, are still emerging. Studies and experiments on developed solutions related to this field have been limited to animal and clinical trials. In this review paper, recent advances in physical stimulation techniques and their effects on the outcome of the DO treatment in MRA are surveyed. By studying the effects of using assisting techniques during the DO treatment, enabling an ideal assisted DO technique in MRA can be possible. Although mentioned techniques have shown constructive effects during the DO procedure, there is still a need for more research and investigation to be done to fully understand the effects of assisting techniques and advanced technologies for use in an ultimate DO procedure in MRA.

The platelet-rich plasma and mesenchymal stem cell milieu: A review of therapeutic effects on bone healing

Platelet-rich plasma is autologous plasma that contains concentrated platelets compared to whole blood. It is relatively inexpensive to produce, can be easily isolated from whole blood, and can be administered while the patient is in the operating room. Further, because platelet-rich plasma is an autologous therapy, there is minimal risk for adverse reactions to the patient. Platelet-rich plasma has been used to promote bone regeneration due to its abundance of concentrated growth factors that are essential to wound healing. In this review, we summarize the methods for producing platelet-rich plasma and the history of its use in bone regeneration. We also summarize the growth factor profiles derived from platelet-rich plasma, with emphasis on those factors that play a direct role in promoting bone repair within the local fracture environment. In addition, we discuss the potential advantages of combining platelet-rich plasma with mesenchymal stem cells, a multipotent cell type often obtained from bone marrow or fat, to improve craniofacial and long bone regeneration. We detail what is currently known about how platelet-rich plasma influences mesenchymal stem cells in vitro, and then highlight the clinical outcomes of administering platelet-rich plasma and mesenchymal stem cells as a combination therapy to promote bone regeneration in vivo.

Percutaneous CO2 Treatment Accelerates Bone Generation During Distraction Osteogenesis in Rabbits

BACKGROUND

Distraction osteogenesis has been broadly used to treat various structural bone deformities and defects. However, prolonged healing time remains a major problem. Various approaches including the use of low-intensity pulsed ultrasound, parathyroid hormone, and bone morphogenetic proteins (BMPs) have been studied to shorten the treatment period with limited success. Our previous studies of rats have reported that the transcutaneous application of CO2 accelerates fracture repair and bone-defect healing in rats by promoting angiogenesis, blood flow, and endochondral ossification. This therapy may also accelerate bone generation during distraction osteogenesis, but, to our knowledge, no study investigating CO2 therapy on distraction osteogenesis has been reported.

QUESTIONS/PURPOSES

We aimed to investigate the effect of transcutaneous CO2 during distraction osteogenesis in rabbits, which are the most suitable animal as a distraction osteogenesis model for a lengthener in terms of limb size. We asked: Does transcutaneous CO2 during distraction osteogenesis alter (1) radiographic bone density in the distraction gap during healing; (2) callus parameters, including callus bone mineral content, volumetric bone mineral density, and bone volume fraction; (3) the newly formed bone area, cartilage area, and angiogenesis, as well as the expression of interleukin-6 (IL-6), BMP-2, BMP-7, hypoxia-inducible factor (HIF) -1α, and vascular endothelial growth factor (VEGF); and (4) three-point bend biomechanical strength, stiffness, and energy?

METHODS

Forty 24-week-old female New Zealand white rabbits were used according to a research protocol approved by our institutional ethical committee. A distraction osteogenesis rabbit tibia model was created as previously described. Briefly, an external lengthener was applied to the right tibia, and a transverse osteotomy was performed at the mid-shaft. The osteotomy stumps were connected by adjusting the fixator to make no gap. After a 7-day latency phase, distraction was continued at 1 mm per day for 10 days. Beginning the day after the osteotomy, a 20-minute transcutaneous application of CO2 on the operated leg using a CO2 absorption-enhancing hydrogel was performed five times per week in the CO2 group (n = 20). Sham treatment with air was administered in the control group (n = 20). Animals were euthanized immediately after the distraction period (n = 10), 2 weeks (n = 10), and 4 weeks (n = 20) after completion of distraction. We performed bone density quantification on the plain radiographs to evaluate consolidation in the distraction gap with image analyzing software. Callus parameters were measured with micro-CT to assess callus microstructure. The newly formed bone area and cartilage area were measured histologically with safranin O/fast green staining to assess the progress of ossification. We also performed immunohistochemical staining of endothelial cells with fluorescein-labeled isolectin B4 and examined capillary density to evaluate angiogenesis. Gene expressions in newly generated callus were analyzed by real-time polymerase chain reaction. Biomechanical strength, stiffness, and energy were determined from a three-point bend test to assess the mechanical strength of the callus.

RESULTS

Radiographs showed higher pixel values in the distracted area in the CO2 group than the control group at Week 4 of the consolidation phase (0.98 ± 0.11 [95% confidence interval 0.89 to 1.06] versus 1.19 ± 0.23 [95% CI 1.05 to 1.34]; p = 0.013). Micro-CT demonstrated that bone volume fraction in the CO2 group was higher than that in the control group at Week 4 (5.56 ± 3.21 % [95% CI 4.32 to 6.12 %] versus 11.90 ± 3.33 % [95% CI 9.63 to 14.25 %]; p = 0.035). There were no differences in any other parameters (that is, callus bone mineral content at Weeks 2 and 4; volumetric bone mineral density at Weeks 2 and 4; bone volume fraction at Week 2). At Week 2, rabbits in the CO2 group had a larger cartilage area compared with those in the control group (2.09 ± 1.34 mm [95% CI 1.26 to 2.92 mm] versus 5.10 ± 3.91 mm [95% CI 2.68 to 7.52 mm]; p = 0.011). More newly formed bone was observed in the CO2 group than the control group at Week 4 (68.31 ± 16.32 mm [95% CI 58.19 to 78.44 mm] versus 96.26 ± 19.37 mm [95% CI 84.25 to 108.26 mm]; p < 0.001). There were no differences in any other parameters (cartilage area at Weeks 0 and 4; newly formed bone area at Weeks 0 and 2). Immunohistochemical isolectin B4 staining showed greater capillary densities in rabbits in the CO2 group than the control group in the distraction area at Week 0 and surrounding tissue at Weeks 0 and 2 (distraction area at Week 0, 286.54 ± 61.55 /mm [95% CI 232.58 to 340.49] versus 410.24 ± 55.29 /mm [95% CI 361.78 to 458.71]; p < 0.001; surrounding tissue at Week 0 395.09 ± 68.16/mm [95% CI 335.34 to 454.83] versus 589.75 ± 174.42/mm [95% CI 436.86 to 742.64]; p = 0.003; at Week 2 271.22 ± 169.42 /mm [95% CI 122.71 to 419.73] versus 508.46 ± 49.06/mm [95% CI 465.45 to 551.47]; p < 0.001 respectively). There was no difference in the distraction area at Week 2. The expressions of BMP -2 at Week 2, HIF1-α at Week 2 and VEGF at Week 0 and 2 were greater in the CO2 group than in the control group (BMP -2 at Week 2 3.84 ± 0.83 fold [95% CI 3.11 to 4.58] versus 7.32 ± 1.63 fold [95% CI 5.88 to 8.75]; p < 0.001; HIF1-α at Week 2, 10.49 ± 2.93 fold [95% CI 7.91 to 13.06] versus 20.74 ± 11.01 fold [95% CI 11.09 to 30.40]; p < 0.001; VEGF at Week 0 4.80 ± 1.56 fold [95% CI 3.43 to 6.18] versus 11.36 ± 4.82 fold [95% CI 7.13 to 15.59]; p < 0.001; at Week 2 31.52 ± 8.26 fold [95% CI 24.27 to 38.76] versus 51.05 ± 15.52 fold [95% CI 37.44 to 64.66]; p = 0.034, respectively). There were no differences in any other parameters (BMP-2 at Week 0 and 4; BMP -7 at Weeks 0, 2 and 4; HIF-1α at Weeks 0 and 4; IL-6 at Weeks 0, 2 and 4; VEGF at Week 4). In the biomechanical assessment, ultimate stress and failure energy were greater in the CO2 group than in the control group at Week 4 (ultimate stress 259.96 ± 74.33 N [95% CI 167.66 to 352.25] versus 422.45 ± 99.32 N [95% CI 299.13 to 545.77]; p < 0.001, failure energy 311.32 ± 99.01 Nmm [95% CI 188.37 to 434.25] versus 954.97 ± 484.39 Nmm [95% CI 353.51 to 1556.42]; p = 0.003, respectively). There was no difference in stiffness (216.77 ± 143.39 N/mm [95% CI 38.73 to 394.81] versus 223.68 ± 122.17 N/mm [95% CI 71.99 to 375.37]; p = 0.92).

CONCLUSION

Transcutaneous application of CO2 accelerated bone generation in a distraction osteogenesis model of rabbit tibias. As demonstrated in previous studies, CO2 treatment might affect bone regeneration in distraction osteogenesis by promoting angiogenesis, blood flow, and endochondral ossification.

CLINICAL RELEVANCE

The use of the transcutaneous application of CO2 may open new possibilities for shortening healing time in patients with distraction osteogenesis. However, a deeper insight into the mechanism of CO2 in the local tissue is required before it can be used in future clinical practice.

The Use of Platelet-Rich Plasma for the Treatment of Osteonecrosis of the Femoral Head: A Systematic Review

Background

As a pathological process, osteonecrosis of the femoral head (ONFH) is characterized by the avascularity of the femoral head, cellular necrosis, microfracture, and the collapse of the articular surface. Currently, critical treatment for early-stage ONFH is limited to core decompression. However, the efficacy of core decompression remains controversial. To improve the core decompression efficacy, regenerative techniques such as the use of platelet-rich plasma (PRP) were proposed for early-stage ONFH. As a type of autologous plasma containing concentrations of platelets greater than the baseline, PRP plays an important role in tissue repair, regeneration, and the differentiation of mesenchymal stem cells (MSCs). In this review, we present a comprehensive overview of the operation modes, mechanism, and efficacy of PRP for early-stage ONFH treatment.

Methods

We searched for relevant studies in the PubMed, Web of Science, and Embase databases. By searching these electronic databases, the identification of either clinical or experimental studies evaluating PRP, MSC, core decompression, and ONFH was our goal.

Results

Seventeen studies of PRP and avascular necrosis of the femoral head were evaluated in our review. Ten studies related to the possible mechanism of PRP for treating ONFH were reviewed. Seven studies of the operation modes of PRP in treating ONFH were identified. We reviewed the efficacy of PRP in treating ONFH systematically and made an attempt to compare the PRP operation modes in 7 studies and other operation modes in past studies for early-stage ONFH treatment.

Conclusion

PRP treats ONFH mainly through three mechanisms: inducing angiogenesis and osteogenesis to accelerate bone healing, inhibiting inflammatory reactions in necrotic lesions, and preventing apoptosis induced by glucocorticoids. In addition, as an adjunctive therapy for core decompression, the use of PRP is recommended to improve the treatment of early-stage ONFH patients, especially when combined with stem cells and bone grafts, by inducing osteogenic activity and stimulating the differentiation of stem cells in necrotic lesions.

Characterization of Naturally Occurring Bioactive Factor Mixtures for Bone Regeneration

In this study, the bone-regenerative potential of bioactive factors derived from adipose tissue, platelet-rich plasma (PRP) and conditioned medium from hypoxia-treated human telomerase immortalized bone-marrow-derived mesenchymal stem cells (hTERT-MSC) was investigated in vitro with the aim to develop cost-effective and efficient bone substitutes for optimized regeneration of bone defects. Adipose tissue was harvested from human donors undergoing reconstructive surgery, and adipose tissue extract (ATE) was prepared. Platelet lysates (PL) were produced by repeated freeze-thaw cycles of PRP, and hypoxia-conditioned medium (HCM) was obtained by culturing human telomerase immortalized bone-marrow-derived mesenchymal stromal cells for 5 days with 1% O2. Besides analysis by cytokine and angiogenesis arrays, ELISA was performed. Angiogenic potential was investigated in cocultures of bone-marrow-derived (BM)-MSC and human umbilical vein endothelial cells. Multiple angiogenic proteins and cytokines were detected in all growth factor mixtures. HCM and ATE contained high amounts of angiogenin and CCL2/MCP-1, whereas PL contained high amounts of IGFBP-1. Culturing cells with HCM and ATE significantly increased specific ALP activity of BM-MSC as well as tubule length and junctions of endothelial networks, indicating osteogenic and angiogenic stimulation. To achieve a synergism between chemoattractive potential and osteogenic and angiogenic differentiation capacity, a combination of different growth factors appears promising for potential clinical applications.

Relevant advances in bone lengthening research: a bibliometric analysis of the 100 most-cited articles published from 2001 to 2017

This study aimed to assess the scientific production of bone lengthening research by identifying the most-cited papers. All articles including the term 'bone lengthening' published between 2001 and 2017 were retrieved through the Web of Science database. The 100 most-cited articles on bone lengthening included a total of 4244 citations, with 414 (9.7%) citations in 2017. There was an average of 249.6 citations per year. The articles predominantly addressed biomechanics and bone formation (38). Different surgical techniques, including intramedullary nail (14), Ilizarov (nine), intramedullary skeletal kinetic distractor (ISKD) (six), Taylor spatial frame (6), the PRECICE device (three), and lengthening and submuscular locking plate (three), were the second most-studied topic. Most studies were therapeutic (58), whereas 30 studies were experimental investigations using animal models. Among the clinical studies, case series were predominant (level of evidence IV) (57). This study presents the first bibliometric analysis of the most relevant articles on bone lengthening. The list is relatively comprehensive in terms of identifying the top issues in this field. However, the most influential clinical studies have a poor level of evidence, although a slight tendency toward a better level of evidence has been observed in more recent years.

Autologous platelet-rich plasma induces bone formation of tissue-engineered bone with bone marrow mesenchymal stem cells on beta-tricalcium phosphate ceramics

Background

The purpose of the study is to investigate whether autologous platelet-rich plasma (PRP) can serve as bone-inducing factors to provide osteoinduction and improve bone regeneration for tissue-engineered bones fabricated with bone marrow mesenchymal stem cells (MSCs) and beta-tricalcium phosphate (β-TCP) ceramics. The current study will give more insight into the contradictory osteogenic capacity of PRP.

Methods

The concentration of platelets, platelet-derived growth factor-AB (PDGF-AB), and transforming growth factor-β1 (TGF-β1) were measured in PRP and whole blood. Tissue-engineered bones using MSCs on β-TCP scaffolds in combination with autologous PRP were fabricated (PRP group). Controls were established without the use of autologous PRP (non-PRP group). In vitro, the proliferation and osteogenic differentiation of MSCs on fabricated constructs from six rabbits were evaluated with MTT assay, alkaline phosphatase (ALP) activity, and osteocalcin (OC) content measurement after 1, 7, and 14 days of culture. For in vivo study, the segmental defects of radial diaphyses of 12 rabbits from each group were repaired by fabricated constructs. Bone-forming capacity of the implanted constructs was determined by radiographic and histological analysis at 4 and 8 weeks postoperatively.

Results

PRP produced significantly higher concentration of platelets, PDGF-AB, and TGF-β1 than whole blood. In vitro study, MTT assay demonstrated that the MSCs in the presence of autologous PRP exhibited excellent proliferation at each time point. The results of osteogenic capacity detection showed significantly higher levels of synthesis of ALP and OC by the MSCs in combination with autologous PRP after 7 and 14 days of culture. In vivo study, radiographic observation showed that the PRP group produced significantly higher score than the non-PRP group at each time point. For histological evaluation, significantly higher volume of regenerated bone was found in the PRP group when compared with the non-PRP group at each time point.

Conclusions

Our study findings support the osteogenic capacity of autologous PRP. The results indicate that the use of autologous PRP is a simple and effective way to provide osteoinduction and improve bone regeneration for tissue-engineered bone reconstruction.

Concise Review: Musculoskeletal Stem Cells to Treat Age-Related Osteoporosis

Age‐related (type‐II) osteoporosis is a common and debilitating condition driven in part by the loss of bone marrow (BM) mesenchymal stromal cells (MSC) and their osteoblast progeny, leading to reduced bone formation. Current pharmacological regiments targeting age‐related osteoporosis do not directly treat the disease by increasing bone formation, but instead use bisphosphonates to reduce bone resorption—a treatment designed for postmenopausal (type‐I) osteoporosis. Recently, the bone regenerative capacity of MSCs has been found within a very rare population of skeletal stem cells (SSCs) residing within the larger heterogeneous BM‐MSC pool. The osteoregenerative potential of SSCs would be an ideal candidate for cell‐based therapies to treat degenerative bone diseases such as osteoporosis. However, to date, clinical and translational studies attempting to improve bone formation through cell transplantation have used the larger, nonspecific, MSC pool. In this review, we will outline the physiological basis of age‐related osteoporosis, as well as discuss relevant preclinical studies that use exogenous MSC transplantation with the aim of treating osteoporosis in murine models. We will also discuss results from specific clinical trials aimed at treating other systemic bone diseases, and how the discovery of SSC could help realize the full regenerative potential of MSC therapy to increase bone formation. Finally, we will outline how ancillary clinical trials could be initiated to assess MSC/SSC‐mediated bone formation gains in existing and potentially unrelated clinical trials, setting the stage for a dedicated clinical investigation to treat age‐related osteoporosis. Stem Cells Translational Medicine2017;6:1930–1939

Biomaterial-mediated strategies targeting vascularization for bone repair

Repair of non-healing bone defects through tissue engineering strategies remains a challenging feat in the clinic due to the aversive microenvironment surrounding the injured tissue. The vascular damage that occurs following a bone injury causes extreme ischemia and a loss of circulating cells that contribute to regeneration. Tissue-engineered constructs aimed at regenerating the injured bone suffer from complications based on the slow progression of endogenous vascular repair and often fail at bridging the bone defect. To that end, various strategies have been explored to increase blood vessel regeneration within defects to facilitate both tissue-engineered and natural repair processes. Developments that induce robust vascularization will need to consolidate various parameters including optimization of embedded therapeutics, scaffold characteristics, and successful integration between the construct and the biological tissue. This review provides an overview of current strategies as well as new developments in engineering biomaterials to induce reparation of a functional vascular supply in the context of bone repair.

Regenerate bone stimulation following limb lengthening: a meta-analysis

Background

Limb lengthening with external fixation is performed to treat patients with leg length discrepancy or short stature. Although the procedure has a high rate of success, one potential drawback from limb lengthening is the amount of time spent in the fixation device while regenerate bone consolidates. Although some studies have assessed different treatment modalities, there has not been a study that has systematically evaluated whether low intensity pulsed ultrasound (LIPUS) or pulsed electromagnetic fields (PEMF) have significant effects on regenerate bone growth. The purpose of this study was to evaluate these two non-pharmacological treatment options to stimulate regenerate bone, and to assess whether they affect the treatment time in limb lengthening.

Methods

Utilizing the electronic databases Medline, Embase and Ovid, we performed a literature search for studies describing the application of LIPUS or PEMF following limb lengthening. With the aid of a statistical software package, Forest-Plots were generated to compare the differences in bone healing index with and without the use of regenerate bone stimulation.

Results

A total of 7 studies assessed these two bone stimulation modalities in a cohort of 153 patients. Overall, the mean healing index was 11.7 days/cm faster when using bone stimulation that in the comparison cohorts (33.7 vs 45.4 day, standardized mean difference of 1.16; p = 0.003).

Conclusion

Amongst the drawbacks from limb lengthening is the relatively high rate of non- and delayed-union. Several methods, both pharmacological and non-pharmacological, have been investigated for their potential to stimulate the growth of regenerate bone. After systematically evaluating the limited and heterogeneous current literature, we found that LIPUS and PEMF both decreased the time for bone healing (healing index in days/cm) of the newly formed regenerate bone in an adequately selected cohort of patients that underwent limb lengthening. However, a high number of complications should be noted, which could be attributed to the lengthening procedure or to the additional bone stimulation.

PROSPERO registration number

CRD42016039024

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1259-5) contains supplementary material, which is available to authorized users.

Mandibular distraction osteogenesis assisted by cell-based tissue engineering: a systematic review

OBJECTIVES

To review the advances and limitations of recent investigations on mandibular distraction osteogenesis (MDO) assisted by mesenchymal stem cell (MSC) transplantation.

MATERIALS AND METHODS

Following the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines, the PubMed, Scopus, and Cochrane electronic databases were systematically searched and screened from their inception through August 2014. Searching terms included the following: 'distraction osteogenesis', 'mandible OR mandibular OR jaw', and 'cells', without any other limitations.

RESULTS

Nineteen studies meeting the eligibility criteria were selected from 227 published articles and used for qualitative synthesis. Fifteen of the studies used small animal models (rats or rabbits), while the other four used large animal models (dogs, pigs or sheep). Among these studies, large variations exist in MDO protocol, cell transplantation time, route and quantity, as well as methodology of outcome assessment. Additionally, all studies had certain biases. Nevertheless, the majority of studies found that MSC transplantation enhanced MDO bone regeneration.

CONCLUSION

Evidence from animal studies indicates that MDO may be enhanced by mesenchymal stem cell transplantation, but many questions related to animal models, MDO protocols, and cell transplantation remain to be investigated.

Effects of electric fields on human mesenchymal stem cell behaviour and morphology using a novel multichannel device

The intrinsic piezoelectric nature of collagenous-rich tissues, such as bone and cartilage, can result in the production of small, endogenous electric fields (EFs) during applied mechanical stresses. In vivo, these EFs may influence cell migration, a vital component of wound healing. As a result, the application of small external EFs to bone fractures and cutaneous wounds is actively practiced clinically. Due to the significant regenerative potential of stem cells in bone and cartilage healing, and their potential role in the observed improved healing in vivo post applied EFs, using a novel medium throughput device, we investigated the impacts of physiological and aphysiological EFs on human bone marrow-derived mesenchymal stem cells (hBM-MSCs) for up to 15 hours. The applied EFs had significant impacts on hBM-MSC morphology and migration; cells displayed varying degrees of conversion to a highly elongated phenotype dependent on the EF strength, consistent perpendicular alignment to the EF vector, and definitive cathodal migration in response to EF strengths ≥0.5 V cm(-1), with the fastest migration speeds observed at between 1.7 and 3 V cm(-1). We observed variability in hBM-MSC donor-to-donor responses and overall tolerances to applied EFs. This study thus confirms hBM-MSCs are responsive to applied EFs, and their rate of migration towards the cathode is controllable depending on the EF strength, providing new insight into the physiology of hBM-MSCs and possibly a significant opportunity for the utilisation of EFs in directed scaffold colonisation in vitro for tissue engineering applications or in vivo post implantation.

Involvement of multiple CCN family members in platelets that support regeneration of joint tissues

OBJECTIVES

Platelet-rich plasma (PRP) has been widely used to enhance the regeneration of damaged joint tissues, such as osteoarthritic and rheumatoid arthritic cartilage. The aim of this study is to clarify the involvement of all of the CCN family proteins that are crucially associated with joint tissue regeneration.

METHODS

Cyr61-CTGF-NOV (CCN) family proteins in human platelets and megakaryocytic cells were comprehensively analyzed by Western blotting analysis. Production of CCN family proteins in megakaryocytes in vivo was confirmed by immunofluorescence analysis of mouse bone marrow cells. Effects of CCN family proteins found in platelets on chondrocytes were evaluated by using human chondrocytic HCS-2/8 cells.

RESULTS

Inclusion of CCN2, a mesenchymal tissue regenerator, was confirmed. Of note, CCN3, which counteracts CCN2, was newly found to be encapsulated in platelets. Interestingly, these two family members were not detectable in megakaryocytic cells, but their external origins were suggested. Furthermore, we found for the first time CCN5 and CCN1 that inhibits ADAMTS4 in both platelets and megakaryocytes. Finally, application of a CCN family cocktail mimicking platelets onto HCS-2/8 cells enhanced their chondrocytic phenotype.

CONCLUSIONS

Multiple inclusion of CCN1, 2 and 3 in platelets was clarified, which supports the harmonized regenerative potential of PRP in joint therapeutics.

Umbilical Cord Tissue Offers the Greatest Number of Harvestable Mesenchymal Stem Cells for Research and Clinical Application: A Literature Review of Different Harvest Sites

PURPOSE

Recent years have seen dramatic increases in the techniques used to harvest and isolate human mesenchymal stem cells. As the potential therapeutic aspects of these cells further develop, informative data on the differences in yields between tissue harvest sites and methods will become increasingly valuable. We collected and compared data on cell yields from multiple tissue harvest sites to provide insight into the varying levels of mesenchymal stem cells by tissue and offer primary and alternative tissue types for harvest and clinical application.

METHODS

The PubMed and Medline databases were searched for articles relating to the harvest, isolation, and quantification of human mesenchymal stem cells. Selected articles were analyzed for relevant data, which were categorized according to tissue site and, if possible, standardized to facilitate comparison between sites.

RESULTS

Human mesenchymal stem cell levels in tissue varied widely according to tissue site and harvest method. Yields for adipose tissue ranged from 4,737 cells/mL of tissue to 1,550,000 cells/mL of tissue. Yields for bone marrow ranged from 1 to 30 cells/mL to 317,400 cells/mL. Yields for umbilical cord tissue ranged from 10,000 cells/mL to 4,700,000 cells/cm of umbilical cord. Secondary tissue harvest sites such as placental tissue and synovium yielded results ranging from 1,000 cells/mL to 30,000 cells/mL.

CONCLUSIONS

Variations in allogeneic mesenchymal stem cell harvest levels from human tissues reflect the evolving nature of the field, patient demographic characteristics, and differences in harvest and isolation techniques. At present, Wharton's jelly tissue yields the highest concentration of allogeneic mesenchymal stem cells whereas adipose tissue yields the highest levels of autologous mesenchymal stem cells per milliliter of tissue.

CLINICAL RELEVANCE

This comparison of stem cell levels from the literature offers a primer and guide for harvesting mesenchymal stem cells. Larger mesenchymal stem cell yields are more desirable for research and clinical application.

Demineralized Bone Matrix Injection in Consolidation Phase Enhances Bone Regeneration in Distraction Osteogenesis via Endochondral Bone Formation

Background

Distraction osteogenesis (DO) is a promising tool for bone and tissue regeneration. However, prolonged healing time remains a major problem. Various materials including cells, cytokines, and growth factors have been used in an attempt to enhance bone formation. We examined the effect of percutaneous injection of demineralized bone matrix (DBM) during the consolidation phase on bone regeneration after distraction.

Methods

The immature rabbit tibial DO model (20 mm length-gain) was used. Twenty-eight animals received DBM 100 mg percutaneously at the end of distraction. Another 22 animals were left without further procedure (control). Plain radiographs were taken every week. Postmortem bone dual-energy X-ray absorptiometry and micro-computed tomography (micro-CT) studies were performed at the third and sixth weeks of the consolidation period and histological analysis was performed.

Results

The regenerate bone mineral density was higher in the DBM group when compared with that in the saline injection control group at the third week postdistraction. Quantitative analysis using micro-CT revealed larger trabecular bone volume, higher trabecular number, and less trabecular separation in the DBM group than in the saline injection control group. Cross-sectional area and cortical thickness at the sixth week postdistraction, assessed using micro-CT, were greater in the regenerates of the DBM group compared with the control group. Histological evaluation revealed higher trabecular bone volume and trabecular number in the regenerate of the DBM group. New bone formation was apparently enhanced, via endochondral ossification, at the site and in the vicinity of the injected DBM. DBM was absorbed slowly, but it remained until the sixth postoperative week after injection.

Conclusions

DBM administration into the distraction gap at the end of the distraction period resulted in a significantly greater regenerate bone area, trabecular number, and cortical thickness in the rabbit tibial DO model. These data suggest that percutaneous DBM administration at the end of the distraction period or in the early consolidation period may stimulate regenerate bone formation and consolidation in a clinical situation with delayed bone healing during DO.

Interactions between MSCs and immune cells: implications for bone healing

It is estimated that, of the 7.9 million fractures sustained in the United States each year, 5% to 20% result in delayed or impaired healing requiring therapeutic intervention. Following fracture injury, there is an initial inflammatory response that plays a crucial role in bone healing; however, prolonged inflammation is inhibitory for fracture repair. The precise spatial and temporal impact of immune cells and their cytokines on fracture healing remains obscure. Some cytokines are reported to be proosteogenic while others inhibit bone healing. Cell-based therapy utilizing mesenchymal stromal cells (MSCs) is an attractive option for augmenting the fracture repair process. Osteoprogenitor MSCs not only differentiate into bone, but they also exert modulatory effects on immune cells via a variety of mechanisms. In this paper, we review the current literature on both in vitro and in vivo studies on the role of the immune system in fracture repair, the use of MSCs in the enhancement of fracture healing, and interactions between MSCs and immune cells. Insight into this paradigm can provide valuable clues in identifying cellular and noncellular targets that can potentially be modulated to enhance both natural bone healing and bone repair augmented by the exogenous addition of MSCs.

Cell-based bone regeneration for alveolar ridge augmentation--cell source, endogenous cell recruitment and immunomodulatory function

Alveolar ridge plays a pivotal role in supporting dental prosthesis particularly in edentulous and semi-dentulous patients. However the alveolar ridge undergoes atrophic change after tooth loss. The vertical and horizontal volume of the alveolar ridge restricts the design of dental prosthesis; thus, maintaining sufficient alveolar ridge volume is vital for successful oral rehabilitation. Recent progress in regenerative approaches has conferred marked benefits in prosthetic dentistry, enabling regeneration of the atrophic alveolar ridge. In order to achieve successful alveolar ridge augmentation, sufficient numbers of osteogenic cells are necessary; therefore, autologous osteoprogenitor cells are isolated, expanded in vitro, and transplanted to the specific anatomical site where the bone is required. Recent studies have gradually elucidated that transplanted osteoprogenitor cells are not only a source of bone forming osteoblasts, they appear to play multiple roles, such as recruitment of endogenous osteoprogenitor cells and immunomodulatory function, at the forefront of bone regeneration. This review focuses on the current consensus of cell-based bone augmentation therapies with emphasis on cell sources, transplanted cell survival, endogenous stem cell recruitment and immunomodulatory function of transplanted osteoprogenitor cells. Furthermore, if we were able to control the mobilization of endogenous osteoprogenitor cells, large-scale surgery may no longer be necessary. Such treatment strategy may open a new era of safer and more effective alveolar ridge augmentation treatment options.

Transforming growth factor Beta family: insight into the role of growth factors in regulation of fracture healing biology and potential clinical applications

The transforming growth factor beta (TGF-β) family forms a group of three isoforms, TGF-β1, TGF-β2, and TGF-β3, with their structure formed by interrelated dimeric polypeptide chains. Pleiotropic and redundant functions of the TGF-β family concern control of numerous aspects and effects of cell functions, including proliferation, differentiation, and migration, in all tissues of the human body. Amongst many cytokines and growth factors, the TGF-β family is considered a group playing one of numerous key roles in control of physiological phenomena concerning maintenance of metabolic homeostasis in the bone tissue. By breaking the continuity of bone tissue, a spread-over-time and complex bone healing process is initiated, considered a recapitulation of embryonic intracartilaginous ossification. This process is a cascade of local and systemic phenomena spread over time, involving whole cell lineages and various cytokines and growth factors. Numerous in vivo and in vitro studies in various models analysing cytokines and growth factors' involvement have shown that TGF-β has a leading role in the fracture healing process. This paper sums up current knowledge on the basis of available literature concerning the role of the TGF-β family in the fracture healing process.

Intrastriatal transplantation of adult human neural crest-derived stem cells improves functional outcome in parkinsonian rats

Parkinson's disease (PD) is considered the second most frequent and one of the most severe neurodegenerative diseases, with dysfunctions of the motor system and with nonmotor symptoms such as depression and dementia. Compensation for the progressive loss of dopaminergic (DA) neurons during PD using current pharmacological treatment strategies is limited and remains challenging. Pluripotent stem cell-based regenerative medicine may offer a promising therapeutic alternative, although the medical application of human embryonic tissue and pluripotent stem cells is still a matter of ethical and practical debate. Addressing these challenges, the present study investigated the potential of adult human neural crest-derived stem cells derived from the inferior turbinate (ITSCs) transplanted into a parkinsonian rat model. Emphasizing their capability to give rise to nervous tissue, ITSCs isolated from the adult human nose efficiently differentiated into functional mature neurons in vitro. Additional successful dopaminergic differentiation of ITSCs was subsequently followed by their transplantation into a unilaterally lesioned 6-hydroxydopamine rat PD model. Transplantation of predifferentiated or undifferentiated ITSCs led to robust restoration of rotational behavior, accompanied by significant recovery of DA neurons within the substantia nigra. ITSCs were further shown to migrate extensively in loose streams primarily toward the posterior direction as far as to the midbrain region, at which point they were able to differentiate into DA neurons within the locus ceruleus. We demonstrate, for the first time, that adult human ITSCs are capable of functionally recovering a PD rat model.

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.

Leucocyte-rich and platelet-rich fibrin for the treatment of bisphosphonate-related osteonecrosis of the jaw: a prospective feasibility study

Our aim was to assess the feasibility of using leucocyte-rich and platelet-rich fibrin (L-PRF) for the treatment of bisphosphonate-related osteonecrosis of the jaw (BRONJ) in a single group study. After treatment with L-PRF, the response of each patient was recorded 1 month and 4 months postoperatively. Further assessments were made of the site, stage, concentration of c-terminal crosslinked telopepide of type 1 collagen, and actinomycosis. Among the total of 34 patients, 26 (77%) showed complete resolution, 6 (18%) had delayed resolution, and 2 (6%) showed no resolution. There was a significant association between the response to treatment and the stage of BRONJ (p=0.002) but no other significant associations were detected. This study has shown that it is feasible to use L-PRF for the treatment of BRONJ, but the effectiveness cannot be judged with this study design. Randomised prospective trials are needed to confirm this.

The composite of bone marrow concentrate and PRP as an alternative to autologous bone grafting

One possible alternative to the application of autologous bone grafts represents the use of autologous bone marrow concentrate (BMC). The purpose of our study was to evaluate the potency of autologous platelet-rich plasma (PRP) in combination with BMC. In 32 mini-pigs a metaphyseal critical-size defect was surgically created at the proximal tibia. The animals were allocated to four treatment groups of eight animals each (1. BMC+CPG group, 2. BMC+CPG+PRP group, 3. autograft group, 4. CPG group). In the BMC+CPG group the defect was filled with autologous BMC in combination with calcium phosphate granules (CPG), whereas in the BMC+CPG+PRP group the defect was filled with the composite of autologous BMC, CPG and autologous PRP. In the autograft group the defect was filled with autologous cancellous graft, whereas in the CPG group the defect was filled with CPG solely. After 6 weeks radiological and histomorphometrical analysis showed significantly more new bone formation in the BMC+CPG+PRP group compared to the BMC+CPG group and the CPG group. There were no significant differences between the BMC+CPG+PRP group and the autograft group. In the PRP platelets were enriched significantly about 4.7-fold compared to native blood. In BMC the count of mononuclear cells increased significantly (3.5-fold) compared to the bone marrow aspirate. This study demonstrates that the composite of BMC+CPG+PRP leads to a significantly higher bone regeneration of critical-size defects at the proximal tibia in mini-pigs than the use of BMC+CPG without PRP. Furthermore, within the limits of the present study the composite BMC+CPG+PRP represents a comparable alternative to autologous bone grafting.

Collagen/hydroxyapatite scaffold enriched with polycaprolactone nanofibers, thrombocyte-rich solution and mesenchymal stem cells promotes regeneration in large bone defect in vivo

A three-dimensional scaffold of type I collagen and hydroxyapatite enriched with polycaprolactone nanofibers (Coll/HA/PCL), autologous mesenchymal stem cells (MSCs) in osteogenic media, and thrombocyte-rich solution (TRS) was an optimal implant for bone regeneration in vivo in white rabbits. Nanofibers optimized the viscoelastic properties of the Coll/HA scaffold for bone regeneration. MSCs and TRS in the composite scaffold improved bone regeneration. Three types of Coll/HA/PCL scaffold were prepared: an MSC-enriched scaffold, a TRS-enriched scaffold, and a scaffold enriched with both MSCs and TRS. These scaffolds were implanted into femoral condyle defects 6 mm in diameter and 10-mm deep. Untreated defects were used as a control. Macroscopic and histological analyses of the regenerated tissue from all groups were performed 12 weeks after implantation. The highest volume and most uniform distribution of newly formed bone occurred in defects treated with scaffolds enriched with both MSCs and TRS compared with that in defects treated with scaffolds enriched by either component alone. The modulus of elasticity in compressive testing was significantly higher in the Coll/HA/PCL scaffold than those without nanofibers. The composite Coll scaffold functionalized with PCL nanofibers and enriched with MSCs and TRS appears to be a novel treatment for bone defects.

Stem cell-conditioned medium accelerates distraction osteogenesis through multiple regenerative mechanisms

Distraction osteogenesis (DO) successfully induces large-scale skeletal tissue regeneration, but it involves an undesirably long treatment period. A high-speed DO mouse model (H-DO) with a distraction speed twice that of a control DO model failed to generate new bone callus in the distraction gap. Here we demonstrate that the local administration of serum-free conditioned medium from human mesenchymal stem cells (MSC-CM) accelerated callus formation in the mouse H-DO model. Secretomic analysis identified factors contained in MSC-CM that recruit murine bone marrow stromal cells (mBMSCs) and endothelial cells/endothelial progenitor cells (EC/EPCs), inhibit inflammation and apoptosis, and promote osteoblast differentiation, angiogenesis, and cell proliferation. Functional assays identified MCP-1/-3 and IL-3/-6 as essential factors in recruiting mBMSCs and EC/EPCs. IL-3/-6 also enhanced the osteogenic differentiation of mBMSCs. MSC-CM that had been depleted of MCP-1/-3 failed to recruit mBMSCs, and consequently failed to promote callus formation. Taken together, our data suggest that MSCs produce a broad repertoire of trophic factors with tissue-regenerative activities that accelerate healing in the DO process.

Biodistribution of locally or systemically transplantedosteoblast-like cells

Objectives

In order to ensure safety of the cell-based therapy for bone regeneration, we examined in vivo biodistribution of locally or systemically transplanted osteoblast-like cells generated from bone marrow (BM) derived mononuclear cells.

Methods

BM cells obtained from a total of 13 Sprague-Dawley (SD) green fluorescent protein transgenic (GFP-Tg) rats were culture-expanded in an osteogenic differentiation medium for three weeks. Osteoblast-like cells were then locally transplanted with collagen scaffolds to the rat model of segmental bone defect. Donor cells were also intravenously infused to the normal Sprague-Dawley (SD) rats for systemic biodistribution. The flow cytometric and histological analyses were performed for cellular tracking after transplantation.

Results

Locally transplanted donor cells remained within the vicinity of the transplantation site without migrating to other organs. Systemically administered large amounts of osteoblast-like cells were cleared from various organ tissues within three days of transplantation and did not show any adverse effects in the transplanted rats.

Conclusions

We demonstrated a precise assessment of donor cell biodistribution that further augments prospective utility of regenerative cell therapy.

The Molecular and Cellular Events That Take Place during Craniofacial Distraction Osteogenesis

Summary:

Gradual bone lengthening using distraction osteogenesis principles is the gold standard for the treatment of hypoplastic facial bones. However, the long treatment time is a major disadvantage of the lengthening procedures. The aim of this study is to review the current literature and summarize the cellular and molecular events occurring during membranous craniofacial distraction osteogenesis. Mechanical stimulation by distraction induces biological responses of skeletal regeneration that is accomplished by a cascade of biological processes that may include differentiation of pluripotential tissue, angiogenesis, osteogenesis, mineralization, and remodeling. There are complex interactions between bone-forming osteoblasts and other cells present within the bone microenvironment, particularly vascular endothelial cells that may be pivotal members of a complex interactive communication network in bone. Studies have implicated number of cytokines that are intimately involved in the regulation of bone synthesis and turnover. The gene regulation of numerous cytokines (transforming growth factor-β, bone morphogenetic proteins, insulin-like growth factor-1, and fibroblast growth factor-2) and extracellular matrix proteins (osteonectin, osteopontin) during distraction osteogenesis has been best characterized and discussed. Understanding the biomolecular mechanisms that mediate membranous distraction osteogenesis may guide the development of targeted strategies designed to improve distraction osteogenesis and accelerate bone regeneration that may lead to shorten the treatment duration.

Establishing a bone marrow stromal cell transplant program at the National Institutes of Health Clinical Center

A repository of cryopreserved bone marrow stromal cell (BMSC) products prepared from marrow aspirates of healthy subjects has been created and is being used to treat patients with inflammatory bowel disease, cardiovascular disease, and acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. New methods of manufacturing BMSCs are being investigated including the use of an automated bioreactor for BMSC expansion and the replacement of fetal bovine serum with human platelet lysate as a media supplement. Efforts are also being made to identify markers that can be used to assess the potency of BMSCs.

Injectable bone tissue engineering using expanded mesenchymal stem cells

Patients suffering from bone defects are often treated with autologous bone transplants, but this therapy can cause many complications. New approaches are therefore needed to improve treatment for bone defects, and stem cell therapy presents an exciting alternative approach. Although extensive evidence from basic studies using stem cells has been reported, few clinical applications using stem cells for bone tissue engineering have been developed. We investigated whether injectable tissue-engineered bone (TEB) composed of mesenchymal stem cells (MSCs) and platelet-rich plasma was able to regenerate functional bone in alveolar deficiencies. We performed these studies in animals and subsequently carried out large-scale clinical studies in patients with long-term follow-up; these showed good bone formation using minimally invasive MSC transplantation. All patients exhibited significantly improved bone volume with no side effects. Newly formed bone areas at 3 months were significantly increased over the preoperation baseline (p < .001) and reached levels equivalent to that of native bone. No significant bone resorption occurred during long-term follow-up. Injectable TEB restored masticatory function in patients. This novel clinical approach represents an effective therapeutic utilization of bone tissue engineering.

Growth factors in human serum during operative tibial lengthening with the Ilizarov method

Despite the widespread clinical use of distraction osteogenesis for limb lengthening, the cellular and molecular mechanisms by which this surgical treatment promotes new bone formation in humans are not well understood. The aim of the research was to study the levels of growth factors (GFs) in the serum of patients that were undergoing tibial lengthening with the Ilizarov method of distraction osteogenesis. Those were patients with unilateral congenital discrepancy of the tibia (n = 12), unilateral posttraumatic tibial shortening (n = 7), and healthy patients that underwent cosmetic bilateral tibial lengthening (n = 10). The study established that unlike the congenital group, the posttraumatic group and healthy subjects showed a significantly evident increase in the levels of angiogenic GFs in their serum on day 10 of distraction. In the congenital group, the changes were not significant at this time point. The levels of TGF-α, TGF-β1, and TGF-β2 tended to decrease on day 10 of distraction and on day 30 of the post-distraction period in the cosmetic and posttraumatic groups while they grew in the congenital group. Most dynamic changes in the GFs levels during tibial lengthening were noted in the subjects undergoing cosmetic lengthening, and the least ones were in the congenital group.

Analysis of the karyotype of expanded human adipose-derived stem cells for bone reconstruction of the maxillo-facial region

Mesenchymal stem cells (MSC) and adipose-derived stem cells (ASC) were recently proposed for bone maxillofacial reconstruction in association with biomaterials. For this application MSC must be ex-vivo expanded in order to obtain, for a given volume of implanted biomaterial, a relevant number of bone forming cells. Previously conducted pre-clinical studies suggested that a concentration of 6 x 10(8) ASC associated with 900 mg of anorganic bovine bone (ABB) could be effective for human maxillary sinus floor elevation. A keystone issue to guarantee the quality and safety of Advanced Therapy Medicinal Products containing expanded MSC and ASC is their chromosome stability in culture: this topic has been widely investigated and conflicting results have been published. Abnormal karyotype of human ex-vivo expanded MSC and ASC was found by some authors, while, at the same time, several other studies showed the MSC and ASC karyotype to be normal. It is therefore important that all the results obtained on MSC and ASC karyotype analysis be published. Given this context, the aim of this manuscript, aim of this manuscript is to verify the karyotype stability of ASC in view of their applications in clinical trials. ASC obtained from the adipose tissue of 4 donors were expanded over extended culture time. Based on previous ASC expansions we hypothesized to be able to obtain 6 x 10(8) cells by passage 7. Karyotype analysis of 30 metaphases was planned to be investigated at passage 2, 7, and 15 in all the cultures. No abnormalities were found in the karyotype of two donors at all the passages tested, while a translocation was found in 2 metaphases of a donor at passage 7, but not at passage 15, and in the fourth donor in 5 metaphases a trisomy was found at passage 15. Chromosomal abnormalities were detected only after extended ASC expansion. Whether these anomalies can be related to risk for the patient's safety will have to be demonstrated by in-vivo studies.

Effect of administration of platelet-rich plasma in early phases of distraction osteogenesis: an experimental study in an ovine femur model

BACKGROUND

It has been suggested that platelet-rich plasma (PRP) might enhance bone formation. The aim of this study was to quantify the effect of PRP administered in the early phases of distraction osteogenesis in an ovine femur model.

METHODS

Twenty sheep aged 4 months underwent osteotomy of the femoral diaphysis followed by distraction osteogenesis. The sheep were divided into two groups of 10. One group received three injections of PRP on days 0, 10, and 20 of the procedure (PRP group) and the other received no additional treatment (control group). The results were evaluated by computed tomography (CT) and histology on completion of distraction osteogenesis (day 40). CT evaluation included measurement of the callus and bone density. Femur size was also measured proximally and distally. Histological evaluation was used to quantify osteoblasts, osteoclasts, vascular lumens, and trabecular maturity by zones and to calculate trabecular bone, fibrous tissue, and cartilage ratios.

RESULTS

Radiological and histological evaluation of the regenerate bone showed no significant differences between the PRP group and the control group for any of the variables analysed. The only significant difference detected was a wider femur (increased diaphyseal thickness) at the proximal and distal levels in the PRP group.

CONCLUSION

We found no radiological or histological evidence that the administration of PRP in the early phases of distraction osteogenesis enhances bone formation.

Treatment of partial ulnar collateral ligament tears in the elbow with platelet-rich plasma

BACKGROUND

Studies have demonstrated the potential of platelet-rich plasma (PRP) to heal damaged tissue. To date, there are no published reports of clinical outcomes of partial ulnar collateral ligament (UCL) tears of the elbow treated with PRP.

HYPOTHESIS

Platelet-rich plasma will promote the healing of partial UCL tears and allow a return to play.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Thirty-four athletes with a partial-thickness UCL tear confirmed on magnetic resonance imaging were prospectively followed. All patients had failed at least 2 months of nonoperative treatment and an attempt to return to play. Baseline questionnaires, including the Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow (KJOC) and Disabilities of the Arm, Shoulder and Hand (DASH) measures, were completed by each patient before injection. Baseline ultrasound measurement of the humeral-ulnar joint space was assessed with 10 lb of valgus stress on the elbow. Each patient received a single type 1A PRP injection at the UCL under ultrasound guidance. The same treating physician at a single institution performed all injections with the same PRP preparation used. Patients completed a course of guided physical therapy and were allowed to return to play based on their symptoms and physical examination findings. Outcome scores, including KJOC and DASH scores, were collected after return to play and were compared with baseline scores. Ultrasound measurements were collected at final follow-up and compared with preinjection values.

RESULTS

At an average follow-up of 70 weeks (range, 11-117 weeks), 30 of 34 athletes (88%) had returned to the same level of play without any complaints. The average time to return to play was 12 weeks (range, 10-15 weeks). The average KJOC score improved from 46 to 93 (P < .0001). The average DASH score improved from 21 to 1 (P < .0001). The sports module of the DASH questionnaire improved from 69 to 3 (P < .0001). Medial elbow joint space opening with valgus stress decreased from 28 to 20 mm at final follow-up (P < .0001). The difference in medial elbow joint space opening (stressed vs nonstressed) decreased from 7 to 2.5 mm at final follow-up (P < .0001). One player had persistent UCL insufficiency and underwent ligament reconstruction at 31 weeks after injection.

CONCLUSION

The results of this study indicate that PRP is an effective option to successfully treat partial UCL tears of the elbow in athletes.

In vivo formation of bone and haematopoietic territories by transplanted human bone marrow stromal cells generated in medium with and without osteogenic supplements

Autologous transplantation of human bone marrow stromal cells (BMSCs) has been successfully used for bone reconstruction. However, in order to advance this approach into the mainstream of bone tissue engineering, the conditions for BMSC cultivation and transplantation must be optimized. In a recent report, cultivation with dexamethasone (Dex) significantly increased bone formation by human BMSCs in vivo. Based on this important conclusion, we analysed the data accumulated by our laboratory, where human BMSCs have been routinely generated using media both with and without a combination of two osteogenic supplements: Dex at 10(-8)  m and ascorbic acid phosphate (AscP) at 10(-4)  m. Our data demonstrate that for 22/24 donors, BMSC strains propagated with and without Dex/AscP formed similar amounts of bone in vivo. Thus, human BMSCs do not appear to need to be induced to osteogenic differentiation ex vivo prior to transplantation. Similarly, for 12/14 donors, BMSC strains cultured with and without Dex/AscP formed haematopoietic territories to a comparable extent. While Dex/AscP did not increase bone formation, they significantly stimulated BMSC in vitro proliferation without affecting the number of BMSC colonies formed by the colony-forming units-fibroblasts. We conclude that for the substantial majority of donors, Dex/AscP have no effect on the ability of BMSCs to form bone and myelosupportive stroma in vivo. However, due to increased BMSC proliferation, the total osteogenic population obtained from a single marrow sample is larger after cultivation with Dex/AscP than without them. Secondary to increased BMSC proliferation, Dex/AscP may stimulate bone formation if BMSCs and/or the transplantation system are less than optimal. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.