Distraction osteogenesis of the lower extremity in patients with achondroplasia/hypochondroplasia treated with transplantation of culture-expanded bone marrow cells and platelet-rich plasma

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.

Interventions for improving clinical outcomes and health-related quality-of-life for people living with skeletal dysplasias: an evidence gap map

PURPOSE

Skeletal dysplasias are rare genetic disorders that are characterized by abnormal development of bone and cartilage. There are multiple medical and non-medical treatments for specific symptoms of skeletal dysplasias e.g. pain, as well as corrective surgical procedures to improve physical functioning. The aim of this paper was to develop an evidence-gap map of treatment options for skeletal dysplasias, and their impact on patient outcomes.

METHODS

We conducted an evidence-gap map to identify the available evidence on the impact of treatment options on people with skeletal dysplasias on clinical outcomes (such as increase in height), and dimensions of health-related quality of life. A structured search strategy was applied to five databases. Two reviewers independently assessed articles for inclusion in two stages: titles and abstracts (stage 1), and full text of studies retained at stage 2.

RESULTS

58 studies fulfilled our inclusion criteria. The included studies covered 12 types of skeletal dysplasia that are non-lethal with severe limb deformities that could result in significant pain and numerous orthopaedic interventions. Most studies reported on the effect of surgical interventions (n = 40, 69%), followed by the effect of treatments on dimensions of health quality-of-life (n = 4, 6.8%) and psychosocial functioning (n = 8, 13.8%).

CONCLUSION

Most studies reported on clinical outcomes from surgery for people living with Achondroplasia. Consequently, there are gaps in the literature on the full range of treatment options (including no active treatment), outcomes and the lived experience of people living with other skeletal dysplasias. More research is warranted to examine the impact of treatments on health-related quality-of-life of people living with skeletal dysplasias, including their relatives to enable them to make preference- and valued based decisions about treatment.

The Efficacy of Platelet-Rich Plasma Augmentation in Microfracture Surgery Osteochondral Lesions of the Talus: A Systematic Review and Meta-Analysis

The appropriate surgical management of osteochondral lesions of the talus (OLT) remains a challenge for foot and ankle surgeons. Currently, microfracture (MF) is the first-line operative treatment for small osteochondral lesions. However, the fibrous cartilage regenerated after MF is mechanically inferior to hyaline cartilage regeneration and is susceptible to deterioration over time. Thus, this meta-analysis aimed to elucidate the efficacy of platelet-rich plasma (PRP) augmentation compared with MF only or other adjuvant supplementations combined with the PRP + MF group (others) for the management of OLT. We searched the PubMed, Embase, Web of Science, and Cochrane Library databases for studies that compared the clinical outcomes of patients who underwent MF only and those who underwent PRP or other adjuvant materials such as hyaluronic acid or BST-CarGel. After the screening, four randomized controlled trials and one quasi-randomized controlled trial were included in this review. We used the following tools for clinical evaluation: the American Orthopedic Foot and Ankle Society (AOFAS) score, Ankle-Hindfoot Scale score, Visual Analog Scale (VAS) score for pain, and the Foot and Ankle Ability Measure (FAAM) score. The standardized mean difference (SMD) was used to analyze the differences in outcomes between groups. Patients in the PRP + MF group had superior final VAS and AOFAS scores to the MF only group. (both p < 0.01) However, no significant improvements between baseline and final follow-up were noted in either score. In addition, there was no remarkable difference in the overall FAAM pain measures between the two groups. The PRP + MF and others groups revealed no significant effect differences in the clinical scores. The results of this analysis suggest that PRP + MF would be more favorable and effective than MF only or additional adjuvant supplementation.

Construction and evaluation of a novel tissue-engineered bone device

Tissue-engineered bones (TEB) are a promising strategy for treating large segmental bone defects. However, the application of TEB is greatly limited by technical and logistical issues caused by the viable cells used. The aim of the present study was to devise novel TEB, termed functional TEB (fTEB) using devitalized mesenchymal stem cells (MSCs) with the functional proteins retained. TEB were fabricated by seeding MSCs on demineralized bone matrix (DBM) scaffolds. fTEB were prepared with deep hyperthermia treatment. Total proteins were extracted from fTEB and conditioned media (CM) were prepared. The effects of fTEB-CM on the proliferation, differentiation and migration of host MSCs were assessed. Following lyophilization, the majority of the MSCs were devitalized, but the proteins within the TEB were retained in fTEB. Similar to TEB, fTEB outperformed the DBM in inducing migration, proliferation and osteogenic differentiation in MSCs. The abundance of cytokines in fTEB was also determined. fTEB were shown to be a promising alternative to TEB. Thus, they might serve as off-the-shelf tissue engineering products, meeting the high demands for bone substitutes in the clinical setting.

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.

Progress in biological reconstruction and enhanced bone revitalization for bone defects

Bone defect reconstruction with artificial materials may produce good functional recovery in the short term. Over time, the durability of artificial materials becomes an issue, and therefore, artificial materials cannot be considered a permanent solution to reconstruction. For long-term outcomes, the goal is to regain function, permanence, and form that are as close to normal as possible. Thus, physiological materials are desirable for use in reconstruction. Biological reconstruction involves the use of materials that are modified in vivo following reconstruction of bone defects. The goal is to achieve bone union, bone revival and remodeling, with biointegration of soft tissue and bone. Allograft use has been the mainstay of bone defect reconstruction in most parts of the world, although in some countries like Japan, allogeneic bone is difficult to obtain due to socio-religious concerns. Therefore, we developed new biological reconstruction techniques to overcome this problem. Bone derived from distraction osteogenesis is autologous bone, which must be an ideal reconstruction material for its biological affinity, strength, resilience, and immunity to infection. When applying this method to patients with malignant disease however, it is important to preserve as much of the local soft tissue as possible, and the clinician must be especially careful of infection and callus formation. Liquid nitrogen treatment of tumor-bearing bone produces equal, if not better, bone revitalization compared to other forms of treatment to date. Reconstruction with liquid nitrogen-treated bone involves resecting the diseased bone and returning it to the body following liquid nitrogen treatment (free-freezing method). Another method involves dislocating the joint proximal to the tumor, or cutting the bone while the distal side remains attached to the body and the limb inverted and treated with liquid nitrogen (pedicle freezing method). When both methods are possible, the pedicle freezing method is preferable since it is performed with minimal osteotomy. Our recent research has looked into the possible role of adipose-derived stem cells in promoting bone fusion and revitalization. This method has produced promising results for the future of biological reconstruction.

Physical, Mental, and Social Problems of Adolescent and Adult Patients with Achondroplasia

Patients with achondroplasia (ACH) require various medical interventions throughout the lifetime. Survey of health-related quality of life (HRQoL) in adult ACH patients is essential for the evaluation of treatment outcomes performed during childhood such as growth hormone administration and limb lengthening surgeries, but no study focused on the treatment strategy by analyzing HRQoL of ACH patients. The purpose of this study was to assess whether final height impacted on HRQoL and to evaluate what kinds of medical interventions were positively or negatively associated with HRQoL. We included 184 ACH patients (10-67 years old) who were registered in the patients' associations or who had a medical history of the investigators' institutions, and analyzed HRQoL by using Short Form-36 and patient demographics. Physical component summary (PCS) was significantly lower than the standard values in each age, especially in elderly populations, while mental component summary (MCS) was similar to the standard values. Role/social component summary was deteriorated only in elderly populations. The PCS was improved in the patients who had a height of 140 cm or taller (p < 0.001). The PCS and MCS were strongly associated with the past medical history of spine surgeries (p < 0.001 and p = 0.028, respectively). A treatment strategy would be planned to gain a final height of 140 cm or taller during childhood in combination with growth hormone administration and limb lengthening surgeries. Appropriate medical management for neurological complications of adult ACH patients is required to maintain physical and mental function.

Regenerative medicine in lower limb reconstruction

Bone is a highly specialized connective tissue and has a rare quality as one of the few tissues that can repair without a scar to regain pre-injury structure and function. Despite the excellent healing capacity of bone, tumor, infection, trauma and surgery can lead to significant bone loss requiring skeletal augmentation. Bone loss in the lower limb poses a complex clinical problem, requiring reconstructive techniques to restore form and function. In the past, amputation may have been the only option; however, there is now an array of reconstructive possibilities and cellular therapies available to salvage a limb. In this review, we will evaluate current applications of bone tissue engineering techniques in limb reconstruction and identify potential strategies for future work.

Strategies of enhancing bone regenerate formation in distraction osteogenesis

Distraction osteogenesis (DO) is a commonly used technique in multiple orthopedic sub-specialties, including trauma, oncology and pediatrics. This technique aims to produce new bone formation in the distraction gap in a controlled manner. The issue with this technique has been the high risk of complications, one of which is poor regenerate formation during the distraction process. Although several factors (including patient and operative factors) and techniques (including surgical, mechanical and pharmacological) have been described to ensure successful regenerate formation during the process of DO, these factors are sometimes difficult to control clinically. Our aim from this review is to highlight the different factors that affect DO, modalities to assess the regenerate and review treatment options for poor regenerate in the distraction gap. In addition, we propose a management protocol derived from the available literature that can be used to facilitate the management of inadequate regenerate formation.

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

Clinical dosage of meclozine promotes longitudinal bone growth, bone volume, and trabecular bone quality in transgenic mice with achondroplasia

Achondroplasia (ACH) is the most common short-limbed skeletal dysplasia caused by gain-of-function mutations in the fibroblast growth factor receptor 3 (FGFR3). No effective FGFR3-targeted therapies for ACH are currently available. By drug repositioning strategies, we identified that meclozine, which has been used as an anti-motion-sickness, suppressed FGFR3 signaling in chondrocytes and rescued short-limbed phenotype in ACH mouse model. Here, we conducted various pharmacological tests for future clinical application in ACH. Pharmacokinetic analyses demonstrated that peak drug concentration (C_max) and area under the concentration-time curve (AUC) of 2 mg/kg of meclozine to mice was lower than that of 25 mg/body to human, which is a clinical usage for anti-motion-sickness. Pharmacokinetic simulation studies showed that repeated dose of 2 mg/kg of meclozine showed no accumulation effects. Short stature phenotype in the transgenic mice was significantly rescued by twice-daily oral administration of 2 mg/kg/day of meclozine. In addition to stimulation of longitudinal bone growth, bone volume and metaphyseal trabecular bone quality were improved by meclozine treatment. We confirmed a preclinical proof of concept for applying meclozine for the treatment of short stature in ACH, although toxicity and adverse events associated with long-term administration of this drug should be examined.

Application of platelet-rich plasma with stem cells in bone and periodontal tissue engineering

Presently, there is a high paucity of bone grafts in the United States and worldwide. Regenerating bone is of prime concern due to the current demand of bone grafts and the increasing number of diseases causing bone loss. Autogenous bone is the present gold standard of bone regeneration. However, disadvantages like donor site morbidity and its decreased availability limit its use. Even allografts and synthetic grafting materials have their own limitations. As certain specific stem cells can be directed to differentiate into an osteoblastic lineage in the presence of growth factors (GFs), it makes stem cells the ideal agents for bone regeneration. Furthermore, platelet-rich plasma (PRP), which can be easily isolated from whole blood, is often used for bone regeneration, wound healing and bone defect repair. When stem cells are combined with PRP in the presence of GFs, they are able to promote osteogenesis. This review provides in-depth knowledge regarding the use of stem cells and PRP in vitro, in vivo and their application in clinical studies in the future.

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.

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.

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.

Clinical outcomes of platelet rich plasma (PRP) as an adjunct to microfracture surgery in osteochondral lesions of the talus

PURPOSE

To compare the effect of arthroscopic microfracture surgery alone or in combination with platelet rich plasma (PRP) on functional outcomes in osteochondral lesions of the talus.

METHODS

A total of 35 patients were included in the study. Control subjects (n = 16) received treatment with microfracture surgery alone, while the remaining patients (PRP group, n = 19) were also given PRP. After an average follow-up of 16.2 months (range 12-24 months), patients were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) scoring system, Foot and Ankle Ability Measure (FAAM), and the visual analogue scale (VAS) for pain.

RESULTS

At baseline, AOFAS and FAAM scores were similar in the two groups, whereas pain scores (VAS) were higher in those who were assigned to combined treatment. Despite the latter finding, the combined treatment with PRP resulted in better outcomes in terms of functional scores [AOFAS, 89.2 ± 3.9 vs. 71.0 ± 10.2, (p = 0.001); FAAM overall pain domain, 1.0 (1.0-2.0) vs. 2.5 (1.0-4.0), (p = 0.04); FAAM 15-min walking domain, 1.0 (1.0-2.0) vs. 2.0 (1.0-4.0) (p = 0.001)]; and pain-related scores [VAS, 2.2 ± 0.8 vs. 3.8 ± 1.2, (p = 0.001)] as compared to arthroscopic microfracture surgery alone.

CONCLUSIONS

PRP as an adjunct to arthroscopic microfracture surgery for the treatment of osteochondral lesions of the talus resulted in improved functional score status in the medium-term. Further studies to determine the long-term efficacy of this approach were warranted.

LEVEL OF EVIDENCE

II.

Bone Augmentation in Rabbit Tibia Using Microfixed Cobalt-Chromium Membranes with Whole Blood and Platelet-Rich Plasma

Background: Bone augmentation is a subject of intensive investigation in regenerative bone medicine and constitutes a clinical situation in which autogenous bone grafts or synthetic materials are used to aid new bone formation. Method: Based on a non-critical defect, Co-Cr barrier membranes were placed on six adult Fauve de Bourgogne rabbits, divided into two groups: whole blood and PRP. Three densitometric controls were performed during the experiment. The animals were euthanized at 30, 45, 60, and 110 days. The presence of newly formed bone was observed. Samples for histological studies were taken from the augmentation center. Results: External and internal bone tissue augmentation was observed in almost all cases. Significant differences between PRP- and whole blood–stimulated bone augmentation were not observed. At 60 days, bones with PRP presented higher angiogenesis, which may indicate more proliferation and cellular activity. Conclusion: PRP activates the bone regeneration process under optimized conditions by stimulation of osteoblast proliferation after six weeks, when a significant difference in cellular activity was observed. Membranes could stimulate bone augmentation at the site of placement and in the surrounding areas.

Meclozine promotes longitudinal skeletal growth in transgenic mice with achondroplasia carrying a gain-of-function mutation in the FGFR3 gene

Achondroplasia (ACH) is one of the most common skeletal dysplasias causing short stature owing to a gain-of-function mutation in the FGFR3 gene, which encodes the fibroblast growth factor receptor 3. We found that meclozine, an over-the-counter drug for motion sickness, inhibited elevated FGFR3 signaling in chondrocytic cells. To examine the feasibility of meclozine administration in clinical settings, we investigated the effects of meclozine on ACH model mice carrying the heterozygous Fgfr3(ach) transgene. We quantified the effect of meclozine in bone explant cultures employing limb rudiments isolated from developing embryonic tibiae from Fgfr3(ach) mice. We found that meclozine significantly increased the full-length and cartilaginous primordia of embryonic tibiae isolated from Fgfr3(ach) mice. We next analyzed the skeletal phenotypes of growing Fgfr3(ach) mice and wild-type mice with or without meclozine treatment. In Fgfr3(ach) mice, meclozine significantly increased the body length after 2 weeks of administration. At skeletal maturity, the bone lengths including the cranium, radius, ulna, femur, tibia, and vertebrae were significantly longer in meclozine-treated Fgfr3(ach) mice than in untreated Fgfr3(ach) mice. Interestingly, meclozine also increased bone growth in wild-type mice. The plasma concentration of meclozine during treatment was within the range that has been used in clinical settings for motion sickness. Increased longitudinal bone growth in Fgfr3(ach) mice by oral administration of meclozine in a growth period suggests potential clinical feasibility of meclozine for the improvement of short stature in ACH.

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.

Uncultured autogenous adipose-derived regenerative cells promote bone formation during distraction osteogenesis in rats

BACKGROUND

Adipose-derived stem cells have recently shown differentiation potential in multiple mesenchymal lineages in vitro and in vivo. These cells can be easily isolated in large amounts from autologous adipose tissue and used without culturing or differentiation induction, which may make them relatively easy to use for clinical purposes; however, their use has not been tested in a distraction osteogenesis model.

QUESTION/PURPOSES

The question of this animal study in a rodent model of distraction osteogenesis was whether uncultured adipose-derived regenerative cells (ADRCs), which can easily be isolated in large amounts from autologous adipose tissue and contain several types of stem and regenerative cells, promote bone formation in distraction osteogenesis. We evaluated this using several tools: (1) radiographic analysis of bone density; (2) histological analysis of the callus that formed; (3) biomechanical testing; (4) DiI labeling (a method of membrane staining for postimplant celltracing); and (5) real-time polymerase chain reaction.

METHODS

Sixty rats were randomly assigned to three groups. Physiological saline (control group), Type I collagen gel (collagen group), or a mixture of ADRC and Type I collagen gel (ADRC group) was injected into the distracted callus immediately after distraction termination. To a rat femur an external fixator was applied at a rate of 0.8 mm/day for 8 days.

RESULTS

The bone density of the distracted callus in the ADRC group increased by 46% (p = 0.003, Cohen's d = 10.2, 95% confidence interval [CI] ± 0.180) compared with the control group at 6 weeks after injection. The fracture strength in the ADRC group increased by 66% (p = 0.006, Cohen's d = 1.32, 95% CI ± 0.180) compared with the control group at 6 weeks after injection. Real-time reverse transcription-polymerase chain reaction of the distracted callus from the ADRC group had higher levels of bone morphogenetic protein-2 (7.4 times higher), vascular endothelial growth factor A (6.8 times higher), and stromal cell-derived factor-1 (4.3 times higher). Cell labeling in the newly formed bone showed the ADRCs differentiated into osseous tissue at 3 weeks after injection.

CONCLUSIONS

The injection of ADRCs promoted bone formation in the distracted callus and this mechanism involves both osteogenic differentiation and secretion of humoral factors such as bone morphogenetic protein-2 or vascular endothelial growth factor A that promotes osteogenesis or angiogenesis.

CLINICAL RELEVANCE

The availability of an easily accessible cell source may greatly facilitate the development of new cell-based therapies for regenerative medicine applications in the distraction osteogenesis.

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.

Early and late fracture following extensive limb lengthening in patients with achondroplasia and hypochondroplasia

Two types of fracture, early and late, have been reported following limb lengthening in patients with achondroplasia (ACH) and hypochondroplasia (HCH). We reviewed 25 patients with these conditions who underwent 72 segmental limb lengthening procedures involving the femur and/or tibia, between 2003 and 2011. Gender, age at surgery, lengthened segment, body mass index, the shape of the callus, the amount and percentage of lengthening and the healing index were evaluated to determine predictive factors for the occurrence of early (within three weeks after removal of the fixation pins) and late fracture (> three weeks after removal of the pins). The Mann‑Whitney U test and Pearson's chi-squared test for univariate analysis and stepwise regression model for multivariate analysis were used to identify the predictive factor for each fracture. Only one patient (two tibiae) was excluded from the analysis due to excessively slow formation of the regenerate, which required supplementary measures. A total of 24 patients with 70 limbs were included in the study. There were 11 early fractures in eight patients. The shape of the callus (lateral or central callus) was the only statistical variable related to the occurrence of early fracture in univariate and multivariate analyses. Late fracture was observed in six limbs and the mean time between removal of the fixation pins and fracture was 18.3 weeks (3.3 to 38.4). Lengthening of the tibia, larger healing index, and lateral or central callus were related to the occurrence of a late fracture in univariate analysis. A multivariate analysis demonstrated that the shape of the callus was the strongest predictor for late fracture (odds ratio: 19.3, 95% confidence interval: 2.91 to 128). Lateral or central callus had a significantly larger risk of fracture than fusiform, cylindrical, or concave callus. Radiological monitoring of the shape of the callus during distraction is important to prevent early and late fracture of lengthened limbs in patients with ACH or HCH. In patients with thin callus formation, some measures to stimulate bone formation should be considered as early as possible.

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.

The etiology of short stature affects the clinical outcome of lower limb lengthening using external fixation. A systematic review of 18 trials involving 547 patients

BACKGROUND AND PURPOSE

Distraction osteogenesis (DO) has been used to gain height in short statured individuals. However, there have been no studies comparing the clinical outcome of limb lengthening based on the etiology of the short stature. We assessed whether different underlying diagnoses are associated with varied clinical outcomes in these patients.

METHODS

We performed a systematic review of the literature pertaining to lower limb lengthening using external fixation for short stature. Clinical outcomes including amount of lengthening, healing index (HI), and complications based on the underlying diagnosis for the short stature were documented.

RESULTS

18 clinical studies were included, with 547 patients who underwent 1,581 lower limb segment lengthening procedures. Mean follow-up was 4.3 years. The average age at lengthening was less for individuals with achondroplasia/hypochondroplasia (A/H) (14.5 years) than for those with Turner's syndrome (TS) (18.2 years) or with constitutional short stature (CSS) (21.7 years). Mean height gained was greater in patients with A/H (9.5 cm) than in those with TS (7.7 cm) or CSS (6.1 cm) group. The HI was better in A/H (30.8 days/cm) and CSS (32 days/cm) than in TS (45.1 days/cm). The reported complication rate per segment was lower for A/H (0.68) and TS (0.71) than for CSS (1.06).

INTERPRETATION

Patients with A/H tolerated larger amounts of lengthening with fewer complications than those with other diagnoses.

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.

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.

Locally injection of cell sheet fragments enhances new bone formation in mandibular distraction osteogenesis: a rabbit model

Effective methods to shorten the treatment period of distraction osteogenesis (DO) are needed. To investigate whether injections of osteogenic bone marrow stromal cell (BMSC) sheet fragments could be used to facilitate new bone formation during DO, 30 rabbits underwent bilateral mandibular osteotomy and their mandibles were lengthened at a rate of 0.75 mm/12 h for 6 days after a 5-day latency period. There were three treatment groups (n = 10 for each group): Serum-free medium, dissociated BMSCs, and BMSC sheet fragments. A local injection was conducted with a needle directly into the distracted areas immediately after distraction. Rabbits were sacrificed for examination at 3 and 6 weeks after injection. Gross examination, radiographic evaluation, and micro-CT scanning indicated a significant increase in bony union in the BMSC sheet fragment group, compared with the medium group and the dissociated cell group. The histomorphometric analysis showed more intensive bone formation in the sheet fragment group than the other two groups at each time point. Additionally, the peak load was significantly higher in the fragment group than those in the others. The results show that injection of BMSC sheet fragments promotes bone formation in DO and indicate a promising approach to shorten the treatment period of osteodistraction.

Efficacy of platelet-rich plasma combined with allograft bone in the management of displaced intra-articular calcaneal fractures: a prospective cohort study

To investigate whether platelet-rich plasma (PRP) when used with allograft bone improves the management outcome of displaced intra-articular calcaneal fractures. Over a 7-year period, all displaced type III calcaneal fractures admitted in our department (276 fractures in 254 patients) were randomly divided into three groups according to the plan of management: autograft alone (n = 101), allograft combined with PRP (n = 85), or allograft alone (n = 90). Radiographic imaging and three-dimensional computed tomography were used to assess the thalamic portion, Bohler's angle, the crucial angle of Gissane, and the height, width and length of the calcaneum. The American Orthopedic Foot and Ankle Society (AOFAS) ankle-hind-foot scoring system was used to evaluate the hind foot function at 12, 24, and 72 months postsurgery. At 12 months no significant difference existed in outcome amongst the treatment groups (p > 0.05). However, at 24 and 72 months the results of the autograft, and the allograft combined with PRP, were similar and both were significantly better than that of the allograft alone (p < 0.05). PRP augmented the favorable outcome of allografts in the management of displaced calcaneal fractures, and matched that of autograft used alone. The findings of this study thus support the clinical use of PRP in conjunction with allograft in the treatment of displaced intra-articular calcaneal fractures.

Proliferation and differentiation of human tenocytes in response to platelet rich plasma: an in vitro and in vivo study

Platelet rich plasma (PRP) is the autologous plasma fraction with a platelet-rich cellular component which is enriched with a number of growth factors. Due to its availability and low cost, PRP has become an increasingly popular clinical tool as an alternative source of growth factors for various applications, for example, tendon regeneration but with limited success in clinical trials. The main objective of the current study was to determine whether activated PRP [i.e., platelet rich plasma-clot release (PRCR)] could be used to induce the proliferation and collagen synthesis in human tenocyte in vitro. The advantage of using PRCR is that the platelet-derived bioactive factors are more concentrated and could initiate a more rapid and accelerated healing response than PRP. Our results demonstrated that 10% PRCR treatment accelerated the extent of cell proliferation and collagen production by human tenocytes in vitro. The expression of specific tenocyte markers were similar to conventional fetal bovine serum (FBS)-treated tenocytes implanted in mice within 14 days of implantation in diffusion chambers. Moreover, relatively more collagen fibrils were evident in PRCR-treated tenocytes in vivo as compared to 10% FBS-treated cells. Overall, our feasibility study has indicated that PRCR can induce human tenocyte proliferation and collagen synthesis which could be implemented for future tendon regeneration in reconstructive surgeries.

The use of bone grafts and bone graft substitutes in pediatric orthopaedics: an overview

Bone graft substitutes have become progressively more widely used, and are currently heavily marketed. To make intelligent decisions, a complete knowledge of autograaft and allograft bone healing is essential, including the definition of "sterile". Differences in donor selection and tissue processing may confound the user not familiar with the implications of these different approaches. Specific products include demineralized bone matrix (DBM), specific growth factors (recombinant BMP's), ceramic grafts, and platelet-rich plasma (PRP). There are a number of useful applications of bone graft substitues for pediatric orthopaedists, but the data base is evolving. This paper describes the current status of these products.

Regenerate augmentation with bone marrow concentrate after traumatic bone loss

Distraction osteogenesis after post-traumatic segmental bone loss of the tibia is a complex and time-consuming procedure that is often complicated due to prolonged consolidation or complete insufficiency of the regenerate. The aim of this feasibility study was to investigate the potential of bone marrow aspiration concentrate (BMAC) for percutaneous regenerate augmentation to accelerate bony consolidation of the regenerate. Eight patients (age 22-64) with an average posttraumatic bone defect of 82.4 mm and concomitant risk factors (nicotine abuse, soft-tissue defects, obesity and/or circulatory disorders) were treated with a modified Ilizarov external frame using an intramedullary cable transportation system. At the end of the distraction phase, each patient was treated with a percutaneously injection of autologous BMAC into the centre of the regenerate. The concentration factor was analysed using flow cytometry. The mean follow up after frame removal was 10 (4-15) months. With a mean healing index (HI) of 36.9 d/cm, bony consolidation of the regenerate was achieved in all eight cases. The mean concentration factor of the bone marrow aspirate was 4.6 (SD 1.23). No further operations concerning the regenerate were needed and no adverse effects were observed with the BMAC procedure. This procedure can be used for augmentation of the regenerate in cases of segmental bone transport. Further studies with a larger number of patients and control groups are needed to evaluate a possible higher success rate and accelerating effects on regenerate healing.

Concise review: the clinical application of mesenchymal stem cells for musculoskeletal regeneration: current status and perspectives

Regenerative therapies in the musculoskeletal system are based on the suitable application of cells, biomaterials, and/or factors. For an effective approach, numerous aspects have to be taken into consideration, including age, disease, target tissue, and several environmental factors. Significant research efforts have been undertaken in the last decade to develop specific cell-based therapies, and in particular adult multipotent mesenchymal stem cells hold great promise for such regenerative strategies. Clinical translation of such therapies, however, remains a work in progress. In the clinical arena, autologous cells have been harvested, processed, and readministered according to protocols distinct for the target application. As outlined in this review, such applications range from simple single-step approaches, such as direct injection of unprocessed or concentrated blood or bone marrow aspirates, to fabrication of engineered constructs by seeding of natural or synthetic scaffolds with cells, which were released from autologous tissues and propagated under good manufacturing practice conditions (for example, autologous chondrocyte implantation). However, only relatively few of these cell-based approaches have entered the clinic, and none of these treatments has become a "standard of care" treatment for an orthopaedic disease to date. The multifaceted reasons for the current status from the medical, research, and regulatory perspectives are discussed here. In summary, this review presents the scientific background, current state, and implications of clinical mesenchymal stem cell application in the musculoskeletal system and provides perspectives for future developments.

Arthroscopic management and platelet-rich plasma therapy for avascular necrosis of the hip

PURPOSE

The purpose is to describe a noninvasive arthroscopic procedure as an alternative to open surgery for avascular necrosis of the hip.

METHODS

Patients with grade I or IIA avascular necrosis of the hip are treated by core decompression performed by drilling under fluoroscopic guidance. Liquid platelet-rich plasma (PRP) is delivered through a trocar, saturating the necrotic area. In more severe conditions, the necrotic bone is decompressed and debrided, through a cortical window at the head-neck junction. A composite graft made of autologous bone and PRP is delivered by impactation through the core decompression track. Fibrin membranes are applied to enhance healing of the head-neck window and arthroscopic portals. Platelet-rich plasma is infiltrated in the central compartment.

RESULTS

This arthroscopic approach aids in making diagnosis of the labrum and articular cartilage and permits intra-operative treatment decisions. Visual control permits the precise localization and treatment for the necrotic area allowing cartilage integrity to be preserved.

CONCLUSIONS

Arthroscopic management of avascular necrosis of the femoral head is viable and has significant advantages. Clinical studies should justify the theoretical additional benefits of this approach.

The potential of human fetal mesenchymal stem cells for off-the-shelf bone tissue engineering application

Mesenchymal stem cells (MSCs) have become one of the most promising cell sources for bone tissue engineering (BTE) applications. In this review, we first highlight recent progress in the understanding of MSC biology, their in vivo niche, multi-faceted contribution to fracture healing and bone re-modelling, and their role in BTE. A literature review from clinicaltrials.gov and Pubmed on clinical usage of MSC for both orthopedic and non-orthopedic indications suggests that translational use of MSC for BTE indications is likely to bear fruit in the ensuing decade. Last, we disscuss the profound influence of ontological and antomical origins of MSC on their proliferation and osteogenesis and demonstrated human fetal MSC (hfMSC) as a superior cellular candidate for off-the-shelf BTE applications. This relates to their superior proliferation capacity, more robust osteogenic potential and lower immunogenecity, as compared to MSC from perinatal and postnatal sources. Furthermore, we discuss our experience in developing a hfMSC based BTE strategy with the integrated use of bioreactor-based dynamic priming within macroporous scaffolds, now ready for evaluation in clinical trials. In conclusion, hfMSC is likely the most promising cell source for allogeneic based BTE application, with proven advantages compared to other MSC based ones.

Bone regeneration: stem cell therapies and clinical studies in orthopaedics and traumatology

Regenerative medicine seeks to repair or replace damaged tissues or organs, with the goal to fully restore structure and function without the formation of scar tissue. Cell based therapies are promising new therapeutic approaches in regenerative medicine. By using mesenchymal stem cells, good results have been reported for bone engineering in a number of clinical studies, most of them investigator initiated trials with limited scope with respect to controls and outcome. With the implementation of a new regulatory framework for advanced therapeutic medicinal products, the stage is set to improve both the characterization of the cells and combination products, and pave the way for improved controlled and well-designed clinical trials. The incorporation of more personalized medicine approaches, including the use of biomarkers to identify the proper patients and the responders to treatment, will be contributing to progress in the field. Both translational and clinical research will move the boundaries in the field of regenerative medicine, and a coordinated effort will provide the clinical breakthroughs, particularly in the many applications of bone engineering.

Methods to shorten the duration of an external fixator in the management of tibial infections

Massive segmental bone loss due to chronic osteomyelitis represents a considerable challenge to orthopedic surgeons and is a limb threatening condition. The only option available in such a clinical situation is segment transport using the Ilizarov technique of distraction osteogenesis; yet the most common problem in cases of bone transport with the Ilizarov technique in massive bone loss, is the long duration of the fixator. In addition to autologous bone grafting, several mechanical, biologic, and external physical treatment modalities may be employed to promote bone formation and maturation during segment transport in osteomyelitis patients. Mechanical approaches include compressive loading of the distraction regenerate, increased frequency of small increments of distraction, and compression-distraction. Intramedullary nailing and hemicorticotomy can reduce the time in external fixation; however, these techniques are associated with technical difficulties and complications. Exogenous application of low-intensity pulsed ultrasound or pulsed electromagnetic fields may shorten the duration of external fixation. Other promising modalities include diphosphonates, physician-directed use (off-label use) of bone morphogenetic proteins, and local injection of bone marrow aspirate and platelet gel at the osteotomy site. Well-designed clinical studies are needed to establish safe and effective guidelines for various modalities to enhance new bone formation during distraction osteogenesis after segment transfer.

Enhancing bone healing during distraction osteogenesis with platelet-rich plasma

Gradual limb lengthening with external fixators using distraction osteogenesis principles is the gold standard for treatment of limb-length discrepancy. However, long treatment time is a major disadvantage of the current lengthening procedures. Efforts to decrease the treatment include biological and biomechanical factors. Injection of platelet-rich plasma (PRP) is a biological method to enhance bone healing during distraction osteogenesis. We hypothesised that PRP can enhance bone healing during limb lengthening. We report our experience with the use of PRP during distraction osteogenesis. This retrospective study included 19 patients divided into the standard group of 10 patients who did not receive PRP and the PRP group of nine patients who received PRP at the end of the distraction phase. The study variables included external fixator time, external fixation index, and complications during treatment. The PRP group had statistically significantly shorter treatment time (p=0.0412). Injection of PRP into regenerate bone might be an effective method to shorten treatment time during limb lengthening and lead to better functional outcomes and improved patient satisfaction.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Skeletal tissue regeneration: current approaches, challenges, and novel reconstructive strategies for an aging population

Loss of skeletal tissue as a consequence of trauma, injury, or disease is a significant cause of morbidity with often wide-ranging socioeconomic impacts. Current approaches to replace or restore significant quantities of lost bone come with substantial limitations and inherent disadvantages that may in themselves cause further disability. In addition, the spontaneous repair capacity of articular cartilage is limited; thus, investigation into new cartilage replacement and regeneration techniques are warranted. Along with the challenges of an increasingly aging demographic, changing clinical scenarios and rising functional expectations provide the imperative for new, more reliable skeletal regeneration strategies. The science of tissue engineering has expanded dramatically in recent years, notably in orthopedic applications, and it is clear that new approaches for de novo skeletal tissue formation offer exciting opportunities to improve the quality of life for many, particularly in the face of increasing patient expectations. However, significant scientific, financial, industrial, and regulatory challenges should be overcome before the successful development of an emergent tissue engineering strategy can be realized. We outline current practice for replacement of lost skeletal tissue and the innovative approaches in tissue regeneration that have so far been translated to clinical use, along with a discussion of the significant hurdles that are presented in the process of translating research strategies to the clinic.

Treatment of long bone defects and non-unions: from research to clinical practice

The treatment of long bone defects and non-unions is still a major clinical and socio-economical problem. In addition to the non-operative therapeutic options, such as the application of various forms of electricity, extracorporeal shock wave therapy and ultrasound therapy, which are still in clinical use, several operative treatment methods are available. No consensus guidelines are available and the treatments of such defects differ greatly. Therefore, clinicians and researchers are presently investigating ways to treat large bone defects based on tissue engineering approaches. Tissue engineering strategies for bone regeneration seem to be a promising option in regenerative medicine. Several in vitro and in vivo studies in small and large animal models have been conducted to establish the efficiency of various tissue engineering approaches. Neverthelsss, the literature still lacks controlled studies that compare the different clinical treatment strategies currently in use. However, based on the results obtained so far in diverse animal studies, bone tissue engineering approaches need further validation in more clinically relevant animal models and in clinical pilot studies for the translation of bone tissue engineering approaches into clinical practice.

Autologous bone marrow grafting combined with demineralized bone matrix improves consolidation of docking site after distraction osteogenesis

BACKGROUND

Distraction osteogenesis is used for the reconstruction of extensive osseous defects. Delay in docking site consolidation results in significant prolongation of this surgical procedure. The primary aim of the present study was to retrospectively compare three different treatment options, all aimed at improving and accelerating docking site consolidation. We further sought to clarify whether the application of autologous bone marrow cells combined with demineralized bone matrix would substantially improve docking site consolidation.

METHODS

Between 1995 and 2008, forty-three patients (mean age, 38.28 years) were managed with bone transport for the treatment of a tibial bone defect (mean length, 9.49 cm). The patients were divided into three groups according to the "docking site procedure" used: closed compression (Group A), surgical debridement of the docking site and application of autologous iliac bone graft (Group B), or surgical debridement and local application of bone marrow concentrate and demineralized bone matrix (Group C). Docking site consolidation was assessed both radiographically and clinically, and the results were statistically analyzed.

RESULTS

The median "healing time" required for docking site consolidation was significantly longer in the compression group as compared with the demineralized bone matrix plus bone marrow group (p = 0.021), whereas there was no difference between the other groups. There was no significant difference among the groups in terms of complication rates (p = 0.702). Docking site consolidation was completed prior to regenerate consolidation in nine of the ten patients in Group C and in 13.6% of the patients in Group B, whereas in all of the remaining patients, completion of regenerate healing always preceded docking site consolidation.

CONCLUSIONS

The application of demineralized bone matrix and autologous bone marrow is at least equivalent to autologous cancellous bone graft in terms of substantially reducing docking site healing time compared with closed compression alone. The application of demineralized bone matrix and autologous bone marrow is an effective treatment option, with minimal donor site morbidity, for reducing consolidation time of the docking site in tibial defects treated with distraction osteogenesis.

Concise review: adipose-derived stromal cells for skeletal regenerative medicine

As the average age of the population grows, the incidence of osteoporosis and skeletal diseases continues to rise. Current treatment options for skeletal repair include immobilization, rigid fixation, alloplastic materials, and bone grafts, all which have significant limitations, especially in the elderly. Adipose-derived stromal cells (ASCs) represent a readily available abundant supply of mesenchymal stem cells, which demonstrate the ability to undergo osteogenesis in vitro and in vivo, making ASCs a promising source of skeletal progenitor cells. Current protocols allow for the harvest of over one million cells from only 15 ml of lipoaspirate. Despite the clinical use of ASCs to treat systemic inflammatory diseases, no large human clinical trials exist using ASCs for skeletal tissue engineering. The aim of this review is to define ASCs, to describe the isolation procedure of ASCs, to review the basic biology of their osteogenic differentiation, discuss cell types and scaffolds available for bone tissue engineering, and finally, to explore imaging of ASCs and their potential future role in human skeletal tissue engineering efforts.