Bridging the gap: bone marrow aspiration concentrate reduces autologous bone grafting in osseous defects

Concentrated Bone Marrow Aspirate-Coated Hydroxyapatite for Reconstruction of Small-to-Moderate-Sized Mandibular Defects Caused by the Removal of Benign Pathologies

Purpose:

The aim of this study was to evaluate the bone regeneration potential of concentrated bone marrow aspirate (BMA)-coated hydroxyapatite (HA) for reconstruction of mandibular defects caused by the removal of benign pathologies.

Patients and Methods:

This prospective clinical study included ten patients with histopathologically proven benign pathologies of the mandible measuring <5 cm anteroposteriorly, who were treated with enucleation or marginal resection, followed by autologous concentrated BMA-coated synthetic biphasic HA (HA and beta-tricalcium phosphate) graft placement. Clinical and radiological evaluations of grafted sites of the mandible were done at 1 week, 1, 3, and 6 months postoperatively using Irwin's radiologic staging and grayscale histogram.

Results:

All patients (10/10, 100%) had proper incorporation of the graft with the normal adjacent bone. Grayscale histogram revealed the initial stages of graft resorption, followed by formation of new bone-grafted sites. No complications such as infection and total graft loss were encountered except for one patient who had partial wound dehiscence that responded well to local wound care and resuturing.

Conclusion:

Concentrated BMA-coated synthetic HA effectively promotes bone regeneration in small-to-moderate-sized defects of the mandible.

Advanced Therapy Medicinal Products: A Guide for Bone Marrow-derived MSC Application in Bone and Cartilage Tissue Engineering

Millions of people worldwide suffer from trauma- or age-related orthopedic diseases such as osteoarthritis, osteoporosis, or cancer. Tissue Engineering (TE) and Regenerative Medicine are multidisciplinary fields focusing on the development of artificial organs, biomimetic engineered tissues, and cells to restore or maintain tissue and organ function. While allogenic and future autologous transplantations are nowadays the gold standards for both cartilage and bone defect repair, they are both subject to important limitations such as availability of healthy tissue, donor site morbidity, and graft rejection. Tissue engineered bone and cartilage products represent a promising and alternative approach with the potential to overcome these limitations. Since the development of Advanced Therapy Medicinal Products (ATMPs) such as TE products requires the knowledge of diverse regulation and an extensive communication with the national/international authorities, the aim of this review is therefore to summarize the state of the art on the clinical applications of human bone marrow-derived stromal cells for cartilage and bone TE. In addition, this review provides an overview of the European legislation to facilitate the development and commercialization of new ATMPs.

A novel bimodal approach for treating atrophic bone non-unions with extracorporeal shockwaves and autologous mesenchymal stem cell transplant

We propose a novel approach for the treatment of atrophic bone non-unions via parallel applications of extracorporeal shock wave therapy (ESWT) and an autologous mesenchymal stem cell transplant. The hypothesis resides on the potentiality of shock waves (SWs) to act as a tool for manipulating the patient's mesenchymal stem cells (MSCs). In addition to the conventional physical stimulus achieved by delivering SWs at the site of non-union to stimulate the well-known trophic effects on bone tissue, a series of concomitant ESWT would be administered in tandem at a bone marrow donor site, such as the iliac crest, to precondition resident bone marrow stromal cells (BMSCs) in vivo, priming resident MSCs by enlarging and conditioning their population prior to bone marrow aspiration. The resulting sample could then be treated to further augment cell concentration and injected, under fluoroscopic control, into the non-union site through a percutaneous approach.

Heterotopic bone formation in the musculus latissimus dorsi of sheep using β-tricalcium phosphate scaffolds: evaluation of different seeding techniques

Osseous reconstruction of large bone defects remains a challenge in oral and maxillofacial surgery. In addition to autogenous bone grafts, which despite potential donor-site mobility still represent the gold standard in reconstructive surgery, many studies have investigated less invasive alternatives such as in vitro cultivation techniques. This study compared different types of seeding techniques on pure β-tricalcium phosphate scaffolds in terms of bone formation and ceramic resorption in vivo. Cylindrical scaffolds loaded with autologous cancellous bone, venous blood, bone marrow aspirate concentrate or extracorporeal in vitro cultivated bone marrow stromal cells were cultured in sheep on a perforator vessel of the musculus latissimus dorsi over a 6-month period. Histological and histomorphometric analyses revealed that scaffolds loaded with cancellous bone were superior at promoting heterotopic bone formation and ceramic degradation, with autogenous bone and bone marrow aspirate concentrate inducing in vivo formation of vital bone tissue. These results confirm that autologous bone constitutes the preferred source of osteoinductive and osteogenic material that can reliably induce heterotopic bone formation in vivo.

[Therapeutic utilization of stem cells in orthopedics]

Stem cells are becoming increasingly more important in the field of regenerative medicine. Adult mesenchymal stem cells (MSCs) are harvested predominantly from bone marrow or adipose tissue, are already being used in the clinical setting and have a low potential for side effects. In orthopedics, experience has been gained in the treatment of bone defects, non-unions, cartilage defects, osteoarthritis and tendon pathologies. The current data are derived from case studies and randomized controlled trials are missing; therefore, there are many open questions concerning the optimal cell source, number of cells, administration technique (e.g. injections and matrices) or combinations with growth factors; however, it is evident from the data that MSCs have a positive effect on tissue regeneration and are safe to use.

Building better bone: The weaving of biologic and engineering strategies for managing bone loss

Segmental bone loss remains a challenging clinical problem for orthopaedic trauma surgeons. In addition to the missing bone itself, the local tissues (soft tissue, vascular) are often highly traumatized as well, resulting in a less than ideal environment for bone regeneration. As a result, attempts at limb salvage become a highly expensive endeavor, often requiring multiple operations and necessitating the use of every available strategy (autograft, allograft, bone graft substitution, Masquelet, bone transport, etc.) to achieve bony union. A cost-sensitive, functionally appropriate, and volumetrically adequate engineered substitute would be practice-changing for orthopaedic trauma surgeons and these patients with difficult clinical problems. In tissue engineering and bone regeneration fields, numerous research efforts continue to make progress toward new therapeutic interventions for segmental bone loss, including novel biomaterial development as well as cell-based strategies. Despite an ever-evolving literature base of these new therapeutic and engineered options, there remains a disconnect with the clinical practice, with very few translating into clinical use. A symposium entitled "Building better bone: The weaving of biologic and engineering strategies for managing bone loss," was presented at the 2016 Orthopaedic Research Society Conference to further explore this engineering-clinical disconnect, by surveying basic, translational, and clinical researchers along with orthopaedic surgeons and proposing ideas for pushing the bar forward in the field of segmental bone loss. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1855-1864, 2017.

A systematic review of the clinical applications and complications of bone marrow aspirate concentrate in management of bone defects and nonunions

PURPOSE

Fracture healing encompasses a succession of dynamic multifactorial metabolic events, which ultimately re-establishes the integrity of the biomechanical properties of the bone. Up to 10% of the fractures occurring annually will need additional surgical procedures because of impaired healing. The aim of this article is to review the current literature regarding the use of bone marrow aspirate concentrate (BMAC) and its effectiveness in the management of bone defects.

METHODS

We have included all published clinical literature investigating the development, techniques and applications of BMAC. Language, design and risk of bias did not deter the initial inclusion of any study. Our search was exclusively limited to studies involving human subjects. A PRISMA compliant search was carried out as published in 2009. This included the online databases: PubMed, EMBASE, clinical trial.gov and the Cochrane library from 1960 to the end of May 2015. MeSH terms used included: "Bone" AND "Marrow" AND "Aspirate" AND "Concentrate" AND "Bone Defects" AND "NONUNION". Eligible studies were independently appraised by two authors using the Critical Appraisal Skills Program checklist. For the purpose of narrative review, relevant studies were included irrespective of methodology or level of evidence.

RESULTS

Thirty-four of the 103 (48 PubMed and 55 EMBASE) results yielded by the preliminary search were included. Exclusions included three duplicate records, six letters, 17 non-orthopaedics related studies and four records irrelevant to our search topic. The CASP appraisal confirmed a satisfactory standard of 31 studies. They all had clearly defined objectives, were well designed and conducted appropriately to meet them. The published studies reported the use of BMAC in non-union and fracture healing (15 studies), bone defects (nine studies), spine fusion (two studies), distraction osteogensis (two studies) and complications related to the use of BMAC (seven studies).

CONCLUSIONS

Stem cells found in BMAC have the potential to self-renew, undertake clonal expansion and differentiate into different musculoskeletal tissues. The commercial processing of BMAC needs to be optimized in order to achieve a consistent end product, which will provide predicable and translatable results. The future potential of cell characterization in order to determine the optimum cell for repair/regeneration of bone also needs to be explored.

LEVEL OF EVIDENCE

Systematic Review of minimum level IV studies.

Role of Bone Marrow Aspirate in Orthopedic Trauma

Bone marrow aspirate grafting entails mesenchymal stem cell-containing bone marrow harvesting and injection into a fracture site to promote bone formation. Although the use of bone marrow aspirate in orthopedic trauma is not widespread, an increasing number of studies are reporting clinical success. Advantages of using bone marrow aspirate are that it is readily obtainable, has low harvest morbidity, and can be easily and quickly injected. However, no universally accepted role for its use exists. Future studies directly comparing bone marrow aspirate with conventional techniques are needed to define its role in the treatment of orthopedic trauma patients.

Different performances of CXCR4, integrin-1β and CCR-2 in bone marrow stromal cells (BMSCs) migration by low-intensity pulsed ultrasound stimulation

Low-intensity pulsed ultrasound (LIPUS) is an established therapy for fracture healing where bone marrow stromal cells (BMSCs) migration is crucial to bone regeneration. This work focused on different performances of C-X-C-receptor 4 (CXCR4), integrin-1β and chemokine-chemokine receptor2 (CCR-2) in BMSCs migration by LIPUS stimulation. Single 20-min LIPUS treatment was applied to BMSCs during wound healing assay with or without the inhibitor AMD3100. The migration rate of BMSCs with LIPUS stimulation exhibited a higher closure rate than that of BMSCs without LIPUS stimulation, which was 1.89 μm/h and 1.38 μm/h, respectively. After LIPUS stimulation, significant elevation of the expression of CXCR4, integrin-1β and CCR-2 was observed. When AMD3100 was added, the migration rate of the BMSCs was obviously declined with or without LIPUS treatment. Furthermore, the expression of CXCR4 was significantly down-regulated by AMD3100, while integrin-1β and CCR-2 were less affected. It suggested that the enhancement of the migration of the BMSCs by LIPUS was inhibited by AMD3100. The results confirmed that LIPUS stimulation was able to activate and improve migration of BMSCs. Nevertheless, CXCR4 and both integrin-1β and CCR-2 had different roles in BMSCs migration after LIPUS treatment.

Comparison of fibrin clots derived from peripheral blood and bone marrow

BACKGROUND

Autologous fibrin clots derived from peripheral blood (pb-fibrin clot) and bone marrow (bm-fibrin clot) are thought to be effective for tissue regeneration. However, there is no report detailing the amount of growth factors in pb-/bm-fibrin clot. In this study we evaluated the amount of growth factors in human pb-/bm-fibrin clot, and prove the validity of fibrin clot for clinical use.

METHODS

Human pb-/bm-fibrin clots were obtained during surgery. In the first experiment, enzyme-linked immunosorbent assay (ELISA) was performed for detecting the amount of vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), insulin-like growth factor-1 (IGF-1), fibroblast growth factor basic (bFGF), hepatocyte growth factor (HGF), transforming growth factor-beta (TGF-β), platelet derived-growth factors-AB (PDGF-AB), and stromal cell-derived factor-1 (SDF-1). In the second experiment, the efficacy of fibrin clot on the osteogenic differentiation and fibroblast proliferation was evaluated. Pb-/bm-fibrin clots were incubated in human osteoblast derived from mesenchymal stromal cells (MSCs) or human skin fibroblast. Alizarin red staining and real-time PCR (COL1A1, RUNX2) were performed for the detection of osteogenic potential. Cell-growth assay (WST-8) and real-time PCR (COL1A1) were also performed for the detection of the potential of fibroblast proliferation.

RESULTS

ELISA analysis revealed that the amount of VEGF, HGF, bFGF, IGF-1, and SDF-1 of bm-fibrin clot group is higher than that of pb-fibrin clot group with statistical differences. Besides, we confirmed that bm-fibrin clot has much potential for the osteogenic differentiation and fibroblast proliferation.

CONCLUSION

The positive outcomes confirm the efficacy of pb-/bm-fibrin clot, and bm-fibrin clot was proved to have much potential for tissue regeneration compared with pb-fibrin clot. The current study showed the potential of a strategy for regenerative medicine using bm-fibrin clot.

Evaluation of anatomical and functional results of overlapping anal sphincter repair with or without the injection of bone marrow aspirate concentrate: a case-control study

AIM

Overlapping anal sphincter repair (OASR) is used for treatment of faecal incontinence due to an external anal sphincter (EAS) defect; however, it is not the optimal treatment as its functional results tend to deteriorate significantly with time. The present study aimed to evaluate the effect of local injection of bone marrow aspirate concentrate (BMAC) on the outcome of OASR.

METHOD

We compared a prospective group of 20 patients with EAS defect who were managed with OASR and BMAC injection (group I) with a historical control group of an equal number of patients managed with OASR alone (group II). Patients were assessed preoperatively and during follow-up by the Wexner continence score and endoanal ultrasound. The primary end-points were the improvement of the continence level measured by the Wexner score and the residual EAS defect size measured by endoanal ultrasound.

RESULTS

At the end of follow-up, group I had significantly lower mean postoperative Wexner score (5.4 ± 7.6 vs 10.6 ± 7.4; P = 0.03) and smaller EAS defect percentage (12.2 ± 17.5 vs 18.3 ± 18.9). These findings were statistically significant in patients with a small preoperative EAS defect equal to or less than one-third of the anal circumference. Patients with larger preoperative EAS did not show a significant improvement of the continence level after repair in either group.

CONCLUSION

Augmenting OASR with local injection of BMAC in patients with faecal incontinence caused by an EAS defect, particularly a smaller defect, can improve both functional and anatomical outcomes of OASR.

Assessment of Multipotent Mesenchymal Stromal Cells in Bone Marrow Aspirate From Human Calcaneus

Bone marrow aspirates (BMAs), owing to their innate osteogenic potential, are well-documented supplements to osteoconductive and/or osteoinductive materials. The calcaneal body provides foot and ankle surgeons a convenient harvest site with low morbidity and minimal cost. In the present study, we sought to identify and characterize multipotent mesenchymal stromal cells (MSCs) in BMAs harvested from the human calcaneal body. Ten healthy patients aged 18 to 65 years were enrolled in the present study. BMAs were harvested from the patients without any reported postoperative complications related to the harvest. Cells isolated from all the aspirates were adherent to culture plates and expressed positive MSC surface markers (CD105, CD90, and CD73) and a low level of negative MSC markers (CD34 and CD45). The cells maintained the ability to proliferate and differentiate into cells of mesenchymal lineages. The BMAs from the human calcaneal body offer a healthy source of multipotent MSCs.

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.

Safety and feasibility of cell-based therapy of autologous bone marrow-derived mononuclear cells in plate-stabilized proximal humeral fractures in humans

Background

Local implantation of ex vivo concentrated, washed and filtrated human bone marrow-derived mononuclear cells (BMC) seeded onto β-tricalciumphosphate (TCP) significantly enhanced bone healing in a preclinical segmental defect model. Based on these results, we evaluated in a first clinical phase-I trial safety and feasibility of augmentation with preoperatively isolated autologous BMC seeded onto β-TCP in combination with angle stable plate fixation for the therapy of proximal humeral fractures as a potential alternative to autologous bone graft from the iliac crest.

Methods

10 patients were enrolled to assess whether cell therapy with 1.3 × 10⁶ autologous BMC/ml/ml β-TCP, collected on the day preceding the definitive surgery, is safe and feasible when seeded onto β-TCP in patients with a proximal humeral fracture. 5 follow-up visits for clinical and radiological controls up to 12 weeks were performed.

Results

β-tricalciumphosphate fortification with BMC was feasible and safe; specifically, neither morbidity at the harvest site nor at the surgical wound site were observed. Neither local nor systemic inflammation was noted. All fractures healed within the observation time without secondary dislocation. Three adverse events were reported: one case each of abdominal wall shingles, tendon loosening and initial screw perforation, none of which presumed related to the IND.

Conclusions

Cell therapy with autologous BMC for bone regeneration appeared to be safe and feasible with no drug-related adverse reactions being described to date. The impression of efficacy was given, although the study was not powered nor controlled to detect such. A clinical trial phase-II will be forthcoming in order to formally test the clinical benefit of BMC-laden β-TCP for PHF patients.

Trial registration The study was registered in the European Clinical Trial Register as EudraCT No. 2012-004037-17. Date of registration 30th of August 2012. Informed consent was signed from all patients enrolled.

Effects of hypoxia on osteogenic differentiation of mesenchymal stromal cells used as a cell therapy for avascular necrosis of the femoral head

BACKGROUND AIMS

Avascular necrosis of the femoral head (AVN) occurs as common result of various conditions or develops as a primary entity, with a high freqency in young adults. Because of its tendency toward osteoarthritis requiring total hip arthroplasty, alternative treatments are being advocated, including cell therapy with mesenchymal stromal cells (MSCs). Because osteonecrotic bone is a severely hypoxic tissue, with a 1-3% oxygen tension, the survival and function of multipotent cells is questionable.

METHODS

In this study, the proliferative, immunophenotypic and osteogenic properties of bone marrow (BM)-derived MSCs from a clinical series of patients with AVN were evaluated under in vitro conditions mimicking the hypoxic milieu of AVN to verify the rationale for cell therapy. MSCs retrieved from the iliac crest (BM-MSC) were isolated, expanded and induced to osteogenic differentiation under a 2% pO2 atmosphere (hypoxia) in comparison with the standard 21% pO2 (normoxia) that is routinely used in cell culture assays.

RESULTS

Both proliferation and colony-forming ability were significantly enhanced in hypoxia-exposed BM-MSCs compared with BM-MSCs under normoxia. The expression of bone-related genes, including alkaline phosphatase, Type I collagen, and osteocalcin was significantly increased under hypoxia. Moreover, mineral deposition after osteogenic induction was not hampered, but in some cases even enhanced under low oxygen tension.

CONCLUSIONS

These findings support autologous cell therapy as an effective treatment to stimulate bone healing in the hypoxic microenvironment of AVN.

Bone repair with skeletal stem cells: rationale, progress to date and clinical application

Bone marrow (BM) contains stem cells for both hematopoietic and nonhematopoietic lineages. Hematopoietic stem cells enable hematopoiesis to occur in a controlled manner in order to accurately compensate for the loss of short- as well as long-lived mature blood cells. The physiological role of nonhematopoietic BM stem cells, often referred to as multipotential stromal cells or skeletal stem cells (SSCs), is less understood. According to an authoritative current opinion, the main function of SSCs is to give rise to cartilage, bone, marrow fat and hematopoiesis-supportive stroma, in a specific sequence during embryonic and postnatal development. This review outlines recent advances in the understanding of origins and homeostatic functions of SSCs in vivo and highlights current and future SSC-based treatments for skeletal and joint disorders.

Biopsy Needle Advancement during Bone Marrow Aspiration Increases Mesenchymal Stem Cell Concentration

Point-of-care kits to concentrate bone marrow (BM)-derived mesenchymal stem cells (MSCs) are used clinically in horses. A maximal number of MSCs per milliliter of marrow aspirated might be desired prior to use of a point-of-care system to concentrate MSCs. Our objective was to test a method to increase the number of MSCs per milliliter of marrow collected. We collected two BM aspirates using two different collection techniques from 12 horses. The first collection technique was to aspirate BM from a single site without advancement of the biopsy needle. The second collection technique was to aspirate marrow from multiple sites within the same sternal puncture by advancing the needle 5 mm three times for BM aspiration from four sites. Numbers of MSCs in collected BM were assessed by total nucleated cell count of BM after aspiration, total colony-forming unit-fibroblast (CFU-F) assay, and total MSC number at each culture passage. The BM aspiration technique of four needle advancements during BM aspiration resulted in higher initial nucleated cell counts, more CFU-Fs, and more MSCs at the first passage. There were no differences in the number of MSCs at later passages. Multiple advancements of the BM needle during BM aspiration resulted in increased MSC concentration at the time of BM collection. If a point-of-care kit is used to concentrate MSCs, multiple advancements may result in higher MSC numbers in the BM concentrate after preparation by the point-of-care kit. For culture expanded MSCs beyond the first cell passage, the difference is of questionable clinical relevance.

Advancing biomaterials of human origin for tissue engineering

Biomaterials have played an increasingly prominent role in the success of biomedical devices and in the development of tissue engineering, which seeks to unlock the regenerative potential innate to human tissues/organs in a state of deterioration and to restore or reestablish normal bodily function. Advances in our understanding of regenerative biomaterials and their roles in new tissue formation can potentially open a new frontier in the fast-growing field of regenerative medicine. Taking inspiration from the role and multi-component construction of native extracellular matrices (ECMs) for cell accommodation, the synthetic biomaterials produced today routinely incorporate biologically active components to define an artificial in vivo milieu with complex and dynamic interactions that foster and regulate stem cells, similar to the events occurring in a natural cellular microenvironment. The range and degree of biomaterial sophistication have also dramatically increased as more knowledge has accumulated through materials science, matrix biology and tissue engineering. However, achieving clinical translation and commercial success requires regenerative biomaterials to be not only efficacious and safe but also cost-effective and convenient for use and production. Utilizing biomaterials of human origin as building blocks for therapeutic purposes has provided a facilitated approach that closely mimics the critical aspects of natural tissue with regard to its physical and chemical properties for the orchestration of wound healing and tissue regeneration. In addition to directly using tissue transfers and transplants for repair, new applications of human-derived biomaterials are now focusing on the use of naturally occurring biomacromolecules, decellularized ECM scaffolds and autologous preparations rich in growth factors/non-expanded stem cells to either target acceleration/magnification of the body's own repair capacity or use nature's paradigms to create new tissues for restoration. In particular, there is increasing interest in separating ECMs into simplified functional domains and/or biopolymeric assemblies so that these components/constituents can be discretely exploited and manipulated for the production of bioscaffolds and new biomimetic biomaterials. Here, following an overview of tissue auto-/allo-transplantation, we discuss the recent trends and advances as well as the challenges and future directions in the evolution and application of human-derived biomaterials for reconstructive surgery and tissue engineering. In particular, we focus on an exploration of the structural, mechanical, biochemical and biological information present in native human tissue for bioengineering applications and to provide inspiration for the design of future biomaterials.

Autologous bone marrow stromal cells are promising candidates for cell therapy approaches to treat bone degeneration in sickle cell disease

Osteonecrosis of the femoral head is a frequent complication in adult patients with sickle cell disease (SCD). To delay hip arthroplasty, core decompression combined with concentrated total bone marrow (BM) treatment is currently performed in the early stages of the osteonecrosis. Cell therapy efficacy depends on the quantity of implanted BM stromal cells. For this reason, expanded bone marrow stromal cells (BMSCs, also known as bone marrow derived mesenchymal stem cells) can be used to improve osteonecrosis treatment in SCD patients. In this study, we quantitatively and qualitatively evaluated the function of BMSCs isolated from a large number of SCD patients with osteonecrosis (SCD-ON) compared with control groups (patients with osteonecrosis not related to SCD (ON) and normal donors (N)). BM total nuclear cells and colony-forming efficiency values (CFE) were significantly higher in SCD-ON patients than in age and sex-matched controls. The BMSCs from SCD-ON patients were similar to BMSCs from the control groups in terms of their phenotypic and functional properties. SCD-ON patients have a higher frequency of BMSCs that retain their bone regeneration potential. Our findings suggest that BMSCs isolated from SCD-ON patients can be used clinically in cell therapy approaches. This work provides important preclinical data that is necessary for the clinical application of expanded BMSCs in advanced therapies and medical products.

Recent biological trends in management of fracture non-union

Bone regeneration is a complex, well-orchestrated physiological process of bone formation, which can be seen during normal fracture healing, and is involved in continuous remodelling throughout adult life. Currently, there is a plethora of different strategies to augment the impaired or “insufficient” bone-regeneration process, including the “gold standard” autologous bone graft, free fibula vascularised graft, allograft implantation, and use of growth factors, osteoconductive scaffolds, osteoprogenitor cells and distraction osteogenesis. Improved “local” strategies in terms of tissue engineering and gene therapy, or even “systemic” enhancement of bone repair, are under intense investigation, in an effort to overcome the limitations of the current methods, to produce bone-graft substitutes with biomechanical properties that are as identical to normal bone as possible, to accelerate the overall regeneration process, or even to address systemic conditions, such as skeletal disorders and osteoporosis. An improved understanding of the molecular and cellular events that occur during bone repair and remodeling has led to the development of biologic agents that can augment the biological microenvironment and enhance bone repair. Orthobiologics, including stem cells, osteoinductive growth factors, osteoconductive matrices, and anabolic agents, are available clinically for accelerating fracture repair and treatment of compromised bone repair situations like delayed unions and nonunions. A lack of standardized outcome measures for comparison of biologic agents in clinical fracture repair trials, frequent off-label use, and a limited understanding of the biological activity of these agents at the bone repair site have limited their efficacy in clinical applications.

Characterization and cytocompatibility of a new injectable multiphasic bone substitute based on a combination of polysaccharide gel-coated OSPROLIFE(®) HA/TTCP granules and bone marrow concentrate

The purpose of this study was to examine the in vitro cytocompatibility of a novel injectable multiphasic bone substitute (MBS) based on polysaccharide gel-coated OSPROLIFE(®) hydroxyapatite (HA)/tetracalcium phosphate (TTCP) granules combined with bone marrow concentrate (BMC). Polysaccharide gel-coated granules loaded in syringe were combined with BMC diluted in ionic crosslinking solution. The product was then maintained in culture to investigate the cytocompatibility, distribution, and osteogenic differentiation function of cells contained in the BMC. The in vitro cytocompatibility was assessed after 0, 24, and 96 h from the injectable MBS preparation using the LIVE/DEAD(®) staining kit. The results highlighted that cells remained viable after combination with the polysaccharide gel-coated granules; also, viability was maintained over time. The distribution of the cells in the product, observed using confocal microscopy, showed viable cells immersed in the polysaccharide gel formed between the granules after ionic crosslinking. The mesenchymal stromal cells (MSC) contained in the injectable MBS, the basic elements for bone tissue regeneration, were able to differentiate toward osteoblasts, producing an osteogenic matrix as evidenced by alizarin red-s (AR-S) staining. In conclusion, we found that the injectable MBS may have the potential to be used as a bone substitute by applying a "one-step" procedure in bone tissue engineering applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 894-902, 2016.

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 therapy by implanted human bone marrow-derived mononuclear cells improved bone healing of large bone defects in rats

QUESTION/AIM: Cell-based therapy by cultivated stem cells (mesenchymal stem cells [MSC] and endothelial progenitor cells [EPC]) in a large-sized bone defect has already shown improved vascularization and new bone formation. However, these methods are clinically afflicted with disadvantages. Another heterogeneous bone marrow cell population, the so-called human bone marrow-derived mononuclear cells (BMC), has nevertheless been used clinically and showed improved vascularization in ischemic limbs or in the myocardium. For clinical use, a certified process has been established; thus, BMC were isolated from bone marrow aspirate by density gradient centrifugation, washed, cleaned, and given back to patients within several hours. This investigation tested the ability of human BMC seeded on beta-tricalcium phosphate (β-TCP) and placed into a large bone defect in rats to improve the bone healing process in vivo.

METHODS

Human EPC were isolated from buffy coat, and MSC or BMC, respectively, were isolated from bone marrow aspirate by density gradient centrifugation. 1.0×10(6) cells were loaded onto 750 μL β-TCP (0.7-1.4 mm). Large femoral defects (6 mm) in athymic rats were created surgically and stabilized with an internal fixateur. The remaining defects were filled with β-TCP granules alone (group 1), β-TCP+EPC/MSC (group 2), or β-TCP+BMC (group 3). After 8 weeks, histomorphometric analysis (new bone formation), radiological microcomputer tomography analysis (bony bridging), and biomechanical testing (three-point bending) were achieved. Moreover, a tumorigenicity study was performed to evaluate the safety of BMC implantation after 26 weeks. For statistical analysis, the Kruskal-Wallis test was used.

RESULTS

Eight weeks after implantation of EPC/MSC or BMC, respectively, we detected a more significant new bone formation compared to control. In group 2 and 3, bony bridging of the defect was seen. In the control group, more chondrocytes and osteoid were detected. In the BMC and EPC/MSC group, respectively, less chondrocytes and a significantly more advanced bone formation were observed. The biomechanical stability of the bone regenerate was significantly enhanced if BMC and EPC/MSC, respectively, were implanted compared to control. Moreover, no tumor formation was detected either macroscopically or histologically after 26 weeks of BMC implantation.

DISCUSSION

Implanted BMC suggest that a heterogeneous cell population may provide a powerful cellular therapeutic strategy for bone healing in a large bone defect in humans.

The effect of bone marrow concentrate and hyperbaric oxygen therapy on bone repair

Neoangiogenesis represents an essential part of bone regeneration. Therefore the improvement of neovascularization is the subject of various research approaches. In addition autologous mesenchymal stem cells concentrate in combination with bone substitute materials have been shown to support bone regeneration. In a rabbit model we examined the proposed synergistic effect of hyperbaric oxygen therapy (HBOT) and bone marrow concentrate (BMC) with porous calcium phosphate granules (CPG) on neoangiogenesis and osseous consolidation of a critical- size defect. The animal groups treated with HBOT showed a significantly higher microvessel density (MVD) by immunhistochemistry. Furthermore HBOT groups presented a significantly larger amount of new bone formation histomorphometrically as well as radiologically. We conclude that the increase in perfusion as a result of increased angiogenesis may play a key role in the effects of HBOT and consequently promotes bone healing.

Microstructure, Mechanical, and Biological Properties of Porous Poly(vinylidene fluoride) Scaffolds Fabricated by Selective Laser Sintering

Porous poly(vinylidene fluoride) (PVDF) scaffolds were prepared by selective laser sintering. The effects of laser energy density, ranging from 0.66 to 2.16 J/mm2, on microstructure and mechanical properties were investigated. At low energy density levels, PVDF particles could fuse well and the structure becomes dense with the increase of the energy density. Smoke and defects (such as holes) were observed when the energy density increased above 1.56 J/mm2which indicated decomposition of the PVDF powder. The scaffolds appeared to be light yellow and there was a reduction in tensile strength. The fabricated scaffolds were immersed into simulated body fluid for different time to evaluate biostability. In addition, MG63 cells were seeded and cultured for different days on the scaffolds. The testing results showed that the cells grew and spread well, indicating that PVDF scaffolds had good biocompatibility.

Prostacyclin suppresses twist expression in the presence of indomethacin in bone marrow-derived mesenchymal stromal cells

Background

Iloprost, a stable prostacyclin I₂ analogue, seems to have an osteoblast-protective potential, whereas indomethacin suppresses new bone formation. The aim of this study was to investigate human bone marrow stromal cell (BMSC) proliferation and differentiation towards the osteoblastic lineage by administration of indomethacin and/or iloprost.

Material/Methods

Human bone marrow cells were obtained from 3 different donors (A=26 yrs/m; B=25 yrs/f, C=35 yrs/m) via vacuum aspiration of the iliac crest followed by density gradient centrifugation and flow cytometry with defined antigens (CD105+/73+/45−/14−). The cells were seeded and incubated as follows: without additives (Group 0; donor A/B/C), with 10⁻⁷ M iloprost only (Group 0+ilo; A/B), with indomethacin only in concentrations of 10⁻⁶ M (Group 1, A), 10⁻⁵ M (Group 2, B), 10⁻⁴ M (Group 3, A/B), and together with 10⁻⁷ M iloprost (Groups 4–6, A/B/C). On Day 10 and 28, UV/Vis spectrometric and immunocytochemical assays (4 samples per group and donor) were performed to investigate cell proliferation (cell count measurement) and differentiation towards the osteoblastic lineage (CD34−, CD45−, CD105+, type 1 collagen (Col1), osteocalcin (OC), alkaline phosphatase (ALP), Runx2, Twist, specific ALP-activity).

Results

Indomethacin alone suppressed BMSC differentiation towards the osteoblastic lineage by downregulation of Runx2, Col1, and ALP. In combination with indomethacin, iloprost increased cell proliferation and differentiation and it completely suppressed Twist expression at Day 10 and 28. Iloprost alone did not promote cell proliferation, but moderately enhanced Runx2 and Twist expression. However, the proliferative effects and the specific ALP-activity varied donor-dependently.

Conclusions

Iloprost partially antagonized the suppressing effects of indomethacin on BMSC differentiation towards the osteoblast lineage. It enhanced the expression of Runx2 and, only in the presence of indomethacin, it completely suppressed Twist. Thus, in the treatment of avascular osteonecrosis or painful bone marrow edema, the undesirable effects of indomethacin might be counterbalanced by iloprost.

A prospective comparison of 3 approved systems for autologous bone marrow concentration demonstrated nonequivalency in progenitor cell number and concentration

OBJECTIVES

To evaluate the efficacy of 3 commercially available systems: the Harvest SmartPReP 2 BMAC, Biomet BioCUE, and Arteriocyte Magellan systems. We compared the number and concentration of progenitor cells achieved both before and after centrifugation and the percentage of progenitor cells salvaged after centrifugation.

METHODS

Forty patients, mean age 47 ± 18 years (range: 18-92 years, 19 male/21 female) were prospectively consented for bilateral iliac crest aspiration. The first 20 aspirations compared the Harvest and Biomet systems, and based on those results, the second 20 compared the Harvest and Arteriocyte systems. One system was randomly assigned to each iliac crest. Each system's unique marrow acquisition process and centrifugation mechanism was followed. Samples for analysis were taken both immediately before the marrow was put into the centrifugation system (after acquisition), and after centrifugation. The number of progenitor cells in each sample was estimated by counting the connective tissue progenitors (CTPs).

RESULTS

The Harvest system achieved a significantly greater number and concentration of CTPs both before and after centrifugation when compared to the Biomet system. There was no difference in the percent yield of CTPs after centrifugation. There was no significant difference in the number and concentration of CTPs between the Harvest and Arteriocyte systems before centrifugation, but the Harvest system had a significantly greater number and concentration of CTPs after centrifugation. The Harvest system also had a significantly higher percent yield of CTPs after centrifugation compared with the Arteriocyte system.

CONCLUSIONS

The Harvest system resulted in a greater CTP number and concentration after centrifugation when compared with the Biomet and Arteriocyte systems and may thus provide increased osteogenic and chondrogenic capacity.

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.

Reconstruction of an extensive soft tissue and bone defect of the first metatarsal with the use of Masquelet technique: a case report

The literature regarding reconstruction of foot bone defects is limited. The purpose of this study is to present a case report with an extensive bone defect of the first metatarsal bone which was treated with the use of the induced membrane technique. A 53-year-old man, with comminuted foot grade IIIb open fracture was treated with the Masquelet procedure. At 14 months follow-up, clinical and radiological assessment of the foot revealed osseous healing and no signs of infection, osteolysis or hardware failure. At 18 months follow-up, the patient had no pain and returned to his usual daily activities. The Masquelet procedure provides an effective method of treatment of extensive bone defects of the foot. It can restore the normal length and metatarsal arch minimizing the risk of complications that occurs with other surgical procedures.

LEVEL OF EVIDENCE

Level V, case report.

Bone marrow stem cells added to a hydroxyapatite scaffold result in better outcomes after surgical treatment of intertrochanteric hip fractures

INTRODUCTION

Intertrochanteric hip fractures occur in the proximal femur. They are very common in the elderly and are responsible for high rates of morbidity and mortality. The authors hypothesized that adding an autologous bone marrow stem cells concentrate (ABMC) to a hydroxyapatite scaffold and placing it in the fracture site would improve the outcome after surgical fixation of intertrochanteric hip fractures.

MATERIAL AND METHODS

30 patients were randomly selected and divided into 2 groups of 15 patients, to receive either the scaffold enriched with the ABMC (Group A) during the surgical procedure, or fracture fixation alone (Group B).

RESULTS

There was a statistically significant difference in favor of group A at days 30, 60, and 90 for Harris Hip Scores (HHS), at days 30 and 60 for VAS pain scales, for bedridden period and time taken to start partial and total weight bearing (P < 0.05).

DISCUSSION

These results show a significant benefit of adding a bone marrow enriched scaffold to surgical fixation in intertrochanteric hip fractures, which can significantly reduce the associated morbidity and mortality rates.

CONCLUSION

Bone marrow stem cells added to a hydroxyapatite scaffold result in better outcomes after surgical treatment of intertrochanteric hip fractures.

Bone tissue engineering and regenerative medicine: targeting pathological fractures

Patients with bone diseases have the highest risk of sustaining fractures and of suffering from nonunion bone healing due to tissue degeneration. Current fracture management strategies are limited in design and functionality and do not effectively promote bone healing within a diseased bone environment. Fracture management approaches include pharmaceutical therapy, surgical intervention, and tissue regeneration for fracture prevention, fracture stabilization, and fracture site regeneration, respectively. However, these strategies fail to accommodate the pathological nature of fragility fractures, leading to unwanted side effects, implant failures, and nonunions. To target fragility fractures, fracture management strategies should include bioactive bone substitutes designed for the pathological environment. However, the clinical outcome of these materials must be predictable within various disease environments. Initial development of a targeted treatment strategy should focus on simulating the physiological in vitro bone environment to predict clinical effectiveness of the engineered bone. An in vitro test system can facilitate reduction of implant failures and non-unions in fragility fractures.

The role of erythropoietin and bone marrow concentrate in the treatment of osteochondral defects in mini-pigs

Background

All available treatment options for osteochondral and chondral defects do not restore hyaline cartilage and are limited to decreasing associated pain, and maintaining or improving joint function. The purpose of this study was to evaluate the potential of erythropoietin (EPO) in combination with bone marrow aspiration concentrate (BMAC) in the treatment of osteochondral defects of mini-pigs.

Methods

14 Goettinger mini-pigs, in which a 6×10 mm osteochondral defect in the medial femoral condyle of both knee joints was created, were randomized into four groups: biphasic scaffold alone, scaffold with EPO, scaffold with BMAC and scaffold in combination with EPO and BMAC. After 26 weeks all animals were euthanized and histological slides were evaluated using a modified ÓDriscoll Score.

Results

In the therapy groups, areas of chondrogenic tissue that contained collagen II were present. Adding EPO (p = 0.245) or BMAC (p = 0.099) alone to the scaffold led to a non-significant increase in the score compared to the control group. However, the combination of EPO and BMAC in the implanted scaffold showed a significant improvement (p = 0.02) in the histological score.

Conclusion

The results of our study show that in mini-pigs, the combination of EPO and BMAC leads to an enhanced osteochondral healing. However, additional research is necessary to further improve the repair tissue and to define the role of MSCs and EPO in cartilage repair.

Preparation and characterization of an advanced medical device for bone regeneration

Tridimensional scaffolds can promote bone regeneration as a framework supporting the migration of cells from the surrounding tissue into the damaged tissue and as delivery systems for the controlled or prolonged release of cells, genes, and growth factors. The goal of the work was to obtain an advanced medical device for bone regeneration through coating a decellularized and deproteinized bone matrix of bovine origin with a biodegradable, biocompatible polymer, to improve the cell engraftment on the bone graft. The coating protocol was studied and set up to obtain a continuous and homogeneous polylactide-co-glycolide (PLGA) coating on the deproteinized bone matrix Orthoss® block without occluding pores and decreasing the scaffold porosity. The PLGA-coated scaffolds were characterized for their morphology and porosity. The effects of PLGA polymer coating on cell viability were assessed with the 3-(4,5-dimethyl-2-thiazolyl)-2,5 diphenyl-2H-tetrazolium assay. The polymer solution concentration and the number of polymeric layers were the main variables affecting coating efficiency and porosity of the original decellularized bone matrix. The designed polymer coating protocol did not affect the trabecular structure of the original decellularized bone matrix. The PLGA-coated decellularized bone matrix maintained the structural features, and it improved the ability in stimulating fibroblasts attachment and proliferation.

Can thrombin-activated platelet releasate compensate the age-induced decrease in cell proliferation of MSC?

Mesenchymal progenitor cells (MSCs) are promising for cell-based regeneration therapies. In elderly patients a reduced proliferation of MSCs has been described. Platelet-rich plasma (PRP) contains important factors necessary for osteogenic regeneration. The aim of this study was to find out whether the age-induced decrease in cell proliferation can be compensated by the use of supernatant of centrifuged, activated PRP (tPR). MSCs of donors of three age groups (A: young, 14-16 years, B: middle age, 36-46 years, C: older, 74-83 years) were expanded with 20% FCS alone or supplemented with thrombin-activated platelet releasate (tPR) (1%, 2.5%, and 5%) or platelet-poor plasma (PPP 5%). Cell proliferation and differentiation was measured on days 0, 3, and 7. Proliferation increased significantly in groups A and B with tPR, and non-significantly in group C. The generation times of MSCs of elderly patients were significantly increased in group C compared to groups A and B. Addition of 1% or 2.5% tPR significantly reduced population doubling times of all age groups. Adding tPR stimulates the proliferation rate of MSCs independent of donor age. For juvenile and middle-aged patients this influence was significant. Cells differentiation into osteoblasts was not influenced by addition of tPR.

The early phase influence of bone marrow concentrate on metaphyseal bone healing

Bone marrow concentrate (BMC) contains high densities of progenitor cells. Therefore, in critical size defects BMC may have the potency to support bone healing. The aim of this study was to investigate the effect of BMC in combination with calcium phosphate granules (CPG) on bone defect healing in a metaphyseal long bone defect in mini-pigs. A metaphyseal critical-size bone defect at the proximal tibia of 24 mini-pigs was filled with CPG combined with BMC, CPG solely (control group) or with an autograft. Radiological and histomorphometrical evaluations after 6 weeks (42 days) showed significantly more bone formation in the BMC group in the central area of the defect zone and the cortical defect zone compared to the CPG group. At the same time the resorption rate of CPG increased significantly in the BMC group. Nevertheless, compared to the BMC group the autograft group showed a significantly higher new bone formation radiologically and histomorphometrically. In BMC the count of mononuclear cells was significantly higher compared to the bone marrow aspirate (3.5-fold). The mesenchymal progenitor cell characteristics of the cells in BMC were confirmed by flow cytometry. Cells from BMC created significantly larger colonies of alkaline phosphatase-positive colony forming units (CFU-ALP) (4.4-fold) compared to cells from bone marrow aspirate. Nevertheless, even in the BMC group complete osseous bridging was only detectable in isolated instances of the bone defects. Within the limitations of this study the BMC+CPG composite promotes bone regeneration in the early phase of bone healing significantly better than the isolated application of CPG. However, the addition of BMC does not lead to a solid fusion of the defect in the early phase of bone healing an still does not represent an equal alternative to autologous bone.

Repair of segmental long-bone defects by stem cell concentrate augmented scaffolds: a clinical and positron emission tomography--computed tomography analysis

PURPOSE

Treating segmental long-bone defects remains a major challenge. For defects >3 cm, segmental transport represents the gold standard, even though the method is time consuming and afflicted with several complications. The aim of this study was to evaluate healing of such defects after grafting an osteogenic scaffold previously seeded with stem cell concentrate.

METHODS

We evaluated five patients with segmental long-bone defects (3-14 cm) treated with bone marrow aspirate concentrates (BMAC) seeded onto a bovine xenogenous scaffold. The healing process was monitored by X-rays and positron emission tomography-computed tomography (PET-CT) three months after surgery.

RESULTS

Centrifugation led to a concentration of leukocytes by factor 8.1 ± 7.5. Full weight bearing was achieved 11.3 ± 5.0 weeks after surgery. PET analysis showed an increased influx of fluoride by factor 8.3 ± 6.4 compared with the contralateral side (p < 0.01). Bone density in the cortical area was 75 ± 16 % of the contralateral side (p < 0.03). The patient with the largest defect sustained an implant failure in the distal femur and finally accomplished therapy by segmental transport. He also had the lowest uptake of fluoride of the patient collective (2.2-fold increase).

CONCLUSION

Stem cell concentrates can be an alternative to segmental bone transport. Further studies are needed to compare this method with autologous bone grafting and segmental transport.

Bone marrow aspiration concentrate and platelet rich plasma for osteochondral repair in a porcine osteochondral defect model

BACKGROUND

Bone marrow aspiration concentrate (BMAC) may possess a high potency for cartilage and osseous defect healing because it contains stem cells and multiple growth factors. Alternatively, platelet rich plasma (PRP), which contains a cocktail of multiple growth factors released from enriched activated thrombocytes may potentially stimulate the mesenchymal stem cells (MSCs) in bone marrow to proliferate and differentiate.

METHODS

A critical size osteochondral defect (10×6 mm) in both medial femoral condyles was created in 14 Goettinger mini-pigs. All animals were randomized into the following four groups: biphasic scaffold alone (TRUFIT BGS, Smith & Nephew, USA), scaffold with PRP, scaffold with BMAC and scaffold in combination with BMAC and PRP. After 26 weeks all animals were euthanized and histological slides were cut, stained and evaluated using a histological score and immunohistochemistry.

RESULTS

The thrombocyte number was significantly increased (p = 0.049) in PRP compared to whole blood. In addition the concentration of the measured growth factors in PRP such as BMP-2, BMP-7, VEGF, TGF-β1 and PDGF were significantly increased when compared to whole blood (p<0.05). In the defects of the therapy groups areas of chondrogenic tissue were present, which stained blue with toluidine blue and positively for collagen type II. Adding BMAC or PRP in a biphasic scaffold led to a significant improvement of the histological score compared to the control group, but the combination of BMAC and PRP did not further enhance the histological score.

CONCLUSIONS

The clinical application of BMAC or PRP in osteochondral defect healing is attractive because of their autologous origin and cost-effectiveness. Adding either PRP or BMAC to a biphasic scaffold led to a significantly better healing of osteochondral defects compared with the control group. However, the combination of both therapies did not further enhance healing.

Tissue engineering applications in the management of bone loss

Several conditions in Orthopaedics and Traumatology are characterized by a bone loss. Bone auto- or allo-grafting was considered sufficient to fullfill the defects decades ago; however, large bone defects were challenging for the Surgeons, particularly in case of necessity of structural and biological properties. Bioindusrty proposed over the years synthetic biomaterials, as Demineralized Bone Matrix, bioactive surfaces for implant coponents, and recently recombinant Bone Morphogenetic Proteins. At the same time, the concept of the "biological chamber" and "diamond concept" allowed the scientific community to consider the need of a more complex interaction between scaffolds (matrix), cells (mesenchymal cells), and signaling (growth factors) in order to induce bone regeneration and also to fill small or large bone defects. A brief overview is made on the processes of a physiologic bone metabolism (induction, conduction, osteogenesis), on the latest therapeutical procedures, based on the use of autologous growth factors and cells, and the recent prosthetic or synthetic scaffolds, and the common clinical conditions that may beneficiate of these modern approaches.

Clinical applications of cell-based approaches in alveolar bone augmentation: a systematic review

BACKGROUND

Cell-based approaches, utilizing adult mesenchymal stem cells (MSCs), are reported to overcome the limitations of conventional bone augmentation procedures.

PURPOSE

The study aims to systematically review the available evidence on the characteristics and clinical effectiveness of cell-based ridge augmentation, socket preservation, and sinus-floor augmentation, compared to current evidence-based methods in human adult patients.

MATERIALS AND METHODS

MEDLINE, EMBASE, and CENTRAL databases were searched for related literature. Both observational and experimental studies reporting outcomes of "tissue engineered" or "cell-based" augmentation in ≥5 adult patients alone, or in comparison with non-cell-based (conventional) augmentation methods, were eligible for inclusion. Primary outcome was histomorphometric analysis of new bone formation. Effectiveness of cell-based augmentation was evaluated based on outcomes of controlled studies.

RESULTS

Twenty-seven eligible studies were identified. Of these, 15 included a control group (8 randomized controlled trials [RCTs]), and were judged to be at a moderate-to-high risk of bias. Most studies reported the combined use of cultured autologous MSCs with an osteoconductive bone substitute (BS) scaffold. Iliac bone marrow and mandibular periosteum were frequently reported sources of MSCs. In vitro culture of MSCs took between 12 days and 1.5 months. A range of autogenous, allogeneic, xenogeneic, and alloplastic scaffolds was identified. Bovine bone mineral scaffold was frequently reported with favorable outcomes, while polylactic-polyglycolic acid copolymer (PLGA) scaffold resulted in graft failure in three studies. The combination of MSCs and BS resulted in outcomes similar to autogenous bone (AB) and BS. Three RCTs and one controlled trial reported significantly greater bone formation in cell-based than conventionally grafted sites after 3 to 8 months.

CONCLUSIONS

Based on limited controlled evidence at a moderate-to-high risk of bias, cell-based approaches are comparable, if not superior, to current evidence-based bone grafting methods, with a significant advantage of avoiding AB harvesting. Future clinical trials should additionally evaluate patient-based outcomes and the time-/cost-effectiveness of these approaches.

Effects of directly autotransplanted tibial bone marrow aspirates on bone regeneration and osseointegration of dental implants

OBJECTIVES

Aim of the pilot trial was to evaluate applicability and effects of directly autotransplanted tibial bone marrow (BM) aspirates on the incorporation of porous bovine bone mineral in a sinus lift model and on the osseointegration of dental implants.

MATERIAL AND METHODS

Six edentulous patients with bilaterally severely resorbed maxillae requiring sinus augmentation and implant treatment were included. During surgery, tibial BM was harvested and added to bone substitute material (Bio-Oss(®) ) at the randomly selected test site. At control sites, augmentation was performed with Bio-Oss(®) alone. The cellular content of each BM aspirate was checked for multipotency and surface antigen expression as quality control. Histomorphometric analysis of biopsies from the augmented sites after 3 and 6 months (during implantation) was used to evaluate effects on bone regeneration. Osseointegration of implants was evaluated with Periotest(®) and radiographic means.

RESULTS

Multipotent cellular content in tibial BM aspirates was comparable to that in punctures from the iliac crest. No significant difference in amount of new bone formation and the integration of bone substitute particles was detected histomorphometrically. Periotest(®) values and radiographs showed successful osseointegration of inserted implants at all sites.

CONCLUSION

Directly autotransplanted tibial BM aspirates did not show beneficial regenerative effects in the small study population (N = 6) of the present pilot trial. However, the proximal tibia proved to be a potential donor site for small quantities of BM. Future trials should clarify whether concentration of tibial BM aspirates could effect higher regenerative potency.