Beta-tricalcium Phosphate Granules Research Articles

Bone tissue 3D bioprinting in regenerative dentistry through the perspective of the diamond concept of healing: A narrative review.

Three-dimensional bioprinting technology appears to be a promising solution for the treatment and reconstruction of a wide range of maxillofacial bone defects. In this review, the authors discuss different bioprinting solutions and options in the context of the 4 factors of bone healing: structures or scaffolds, osteogenic cells, growth factors, and stabilization (diamond concept of healing), as well as the influence of a 5th factor - vascularization. Bone is a complex tissue; hence, bone bioprinting may require different technical approaches and mixed methods. Ultraviolet (UV) crosslinkable hydrogels, such as gelatin methacryloyl (GelMA), are among the most promising bioinks; they are enhanced by hydroxyapatite or 1-2.5 mm beta-tricalcium phosphate (β-TCP) granules and porous scaffolds with recommended pore sizes greater than 300 μm. The advantages of mesenchymal stem cells (MSCs) are their significant availability, low tumorigenicity, and great potential for differentiation into osteoblasts or endothelial cells (ECs). Although growth factors require advanced delivery systems, they provide excellent improvement in the functionality of printed tissues. A proper vasculature system supplies cells with oxygen and nutrients, removes waste products, promotes osteogenesis, prevents ischemic necrosis, and improves the mechanical properties of bone. With all of these aspects perfectly balanced and working in synergy, the clinical use of bioprinting is only a matter of time.

Unidirectional porous beta-tricalcium phosphate as a potential bone regeneration material for infectious bony cavity without debridement in pyogenic spondylitis.

An 81-year-old man was initially diagnosed with T11 osteoporotic vertebral fracture. The fractured vertebral body was filled with unidirectional porous beta-tricalcium phosphate (β-TCP) granules, and posterior spinal fixation was conducted using percutaneous pedicle screws. However, the pain did not improve, the inflammatory response increased, and bone destructive changes extended to T10. The correct diagnosis was pyogenic spondylitis with concomitant T11 fragility vertebral fracture. Revision surgery was conducted 2weeks after the initial surgery, the T10 and T11 pedicle screws were removed, and refixation was conducted. After the revision surgery, the pain improved and mobilization proceeded. The infection was suppressed by the administration of sensitive antibiotics. One month after surgery, a lateral bone bridge appeared at the T10/11 intervertebral level. This increased in size over time, and synostosis was achieved at 6months. Resorption of the unidirectional porous β-TCP granules was observed over time and partial replacement with autologous bone was evident from 6months after the revision surgery. Two years and 6months after the revision surgery, although there were some residual β-TCP and bony defect in the center of the vertebral body, the bilateral walls have well regenerated. This suggested that given an environment of sensitive antibiotic administration and restricted local instability, unidirectional porous β-TCP implanted into an infected vertebral body may function as a resorbable bone regeneration scaffold without impeding infection control even without debridement of the infected bony cavity.

Feasibility study on surface morphology regulation of β-tricalcium phosphate bone graft for enhancing cellular response

Beta-tricalcium phosphate (βTCP) granules are commonly used as an artificial bone graft material. Meanwhile, the surface morphology of the bone graft is an important factor for cellular response. In this study, feasibility study on surface morphology regulation of βTCP bone graft for enhancing cellular response were investigated. The regulation was achieved on the basis of a multistep heating process. Briefly, initial heat treatment of βTCP granules at 1300 °C for 12 h resulted in fabrication of alpha-tricalcium phosphate (αTCP) granules with interconnected micropores. In the second heat treatment, exposure of αTCP granules to 100% relative humidity at 100 °C resulted in partial hydrolysis of αTCP, leading to the fabrication of needle-like calcium-deficient hydroxyapatite (cdHAp) crystals on the αTCP surface. After the third heat treatment at 1100 °C, both cdHAp and αTCP converted back to βTCP, and interconnected micropores with a roughened surface structure were formed. In vitro cell evaluation demonstrated that βTCP granules obtained by the series of heat treatments exhibited 24 times higher cell proliferation at day 9, and four times higher alkaline phosphatase activity compared with untreated βTCP granules. Therefore, we concluded that regulation of surface morphology by a series of heat treatments is useful for improving cellular response to βTCP bone grafting materials.

Treatment of complex regional pain syndrome after filling a single bone-cyst cavity with beta-tricalcium phosphate granules

Backgrоund. Сomplex regional pain syndrome is a condition associated with a multitude of clinical factors. Its characteristic feature is persistent pain caused by injuries and is not anatomically limited to the location of a particular peripheral nerve.
 Clinical case. This article describes a case involving the treatment of complex regional pain syndrome in a thirteen-year-old patient, which resulted in a simple bone cyst surgical treatment of the lower-third of the fibula. Diagnostics were based on clinical, laboratorial, histological, radiological, and instrumental methods of research. The treatment methods included medication (nonsteroidal anti-inflammatory drugs, antidepressants, antipsychotics, anticonvulsants, non-opioid analgesics of central action, and bisphosphonates), cold plasma ablation, neurolysis of the sural nerve, prolonged regional anesthesia, tunneling of the bone marrow cavity (filled by substitutional filler), and marginal bone resection.
 Discussion. Сomplex regional pain syndrome is a poorly studied condition, which contributes to the complexity of its diagnosis. In this case, the presence of complex regional pain syndrome can be characterized by tissue injury during surgical intervention as well as by intraoperative injury of the nerve fibers. The stages of complex regional pain syndrome detected in studies may not appear in all patients, and in this case, no staging was observed. By eliminating the obliteration of the medullary canal after segmental resection of the sclerosed portion of the bone, it was possible to reduce the severity of pain, which resulted in the subsequent disappearance of the manifestations of complex regional pain syndrome.
 Conclusions. This case testifies to the effectiveness of various methods of treating complex regional pain syndrome. The etiology of the specific patients pain syndrome should be considered when treating complex regional pain syndrome.

Gas-foamed poly(lactide-co-glycolide) and poly(lactide-co-glycolide) with bioactive glass fibres demonstrate insufficient bone repair in lapine osteochondral defects.

Deep osteochondral defects may leave voids in the subchondral bone, increasing the risk of joint structure collapse. To ensure a stable foundation for the cartilage repair, bone grafts can be used for filling these defects. Poly(lactide-co-glycolide) (PLGA) is a biodegradable material that improves bone healing and supports bone matrix deposition. We compared the reparative capacity of two investigative macroporous PLGA-based biomaterials with two commercially available bone graft substitutes in the bony part of an intra-articular bone defect created in the lapine femur. New Zealand white rabbits (n=40) were randomized into five groups. The defects, 4mm in diameter and 8mm deep, were filled with neat PLGA; a composite material combining PLGA and bioactive glass fibres (PLGA-BGf); commercial beta-tricalcium phosphate (β-TCP) granules; or commercial bioactive glass (BG) granules. The fifth group was left untreated for spontaneous repair. After three months, the repair tissue was evaluated with X-ray microtomography and histology. Relative values comparing the operated knee with its contralateral control were calculated. The relative bone volume fraction (∆BV/TV) was largest in the β-TCP group (p≤0.012), which also showed the most abundant osteoid. BG resulted in improved bone formation, whereas defects in the PLGA-BGf group were filled with fibrous tissue. Repair with PLGA did not differ from spontaneous repair. The PLGA, PLGA-BGf, and spontaneous groups showed thicker and sparser trabeculae than the commercial controls. We conclude that bone repair with β-TCP and BG granules was satisfactory, whereas the investigational PLGA-based materials were only as good as or worse than spontaneous repair.

Role of Beta Tri-calcium Phosphate-based Composite Ceramic as Bone-Graft Expander in Masquelet's-Induced Membrane Technique.

Background:Filling bone defect after debridement of infected nonunion is an orthopedic challenge. Since the volume of autologous bone graft available is limited, allograft, demineralized bone matrix, and calcium phosphate ceramic-based bone graft substitutes have come up as potential autograft expanders. This study was conducted to analyze the use of beta tri-calcium phosphate (B-TCP)-based composite ceramic as autologous bone-graft expander in the management of postinfective segmental gap nonunion of long bones managed with two-stage Masquelet's technique.Materials and Methods:42 consecutive patients with postinfective segmental long bone defects of 4–12 cm managed with Masquelet's-induced membrane technique, operated between February 2012 and June 2015, were included in this prospective case series. During the second stage bone-grafting procedure, iliac crest autograft alone or mixed with B-TCP granules (ratio not exceeding >1:1) was used along with appropriate internal-fixation. Bony union (defined clinicoradiologically as ability to painlessly bear weight on affected limb without support along with bridging of 3 cortices on X-rays) was evaluated.Results:Union was achieved in 80.9% patients (34/42) with index bone grafting. 100% union rate was achieved in patients where only autograft was used (15/15) and in nonsmoker femoral nonunion patients with the use of B-TCP (13/13). The use of B-TCP was associated with higher rate of nonunion in smokers (6/8, 75%) and in tibial nonunions (4/9, 55.5%). All, but one, of 8 patients with nonunion, united after the second-bone grafting procedure.Conclusion:B-TCP is an efficacious and safe autologous bone graft expander in Masquelet's two-stage management of post infective segmental gap nonunion of long bones. Patients should be counseled regarding increased risk of nonunion and need for repeat grafting with its use, especially if they are smokers or site of involvement is tibia.

Fabrication of self-setting β-TCP granular cement using β-TCP granules and sodium hydrogen sulfate solution.

Bridging beta-tricalcium phosphate (β-TCP) granules with dicalcium phosphate dihydrate (DCPD) creates a porous, interconnected β-TCP granular cement (GC) that is useful for reconstructing bone defects: the interconnected pores can accelerate new bone ingrowth and the set cement prevents the loss of granules from the bone defect area. However, the setting time of β-TCP GC in an acidic calcium phosphate solution is too short (<1 min) for handling in clinical applications, such as in orthopedic surgery. To address this issue, we sought to optimize the setting time of β-TCP GC using β-TCP granules and NaHSO4 solution, as [Formula: see text] is a known inhibitor of DCPD formation. Both DCPD and calcium sulfate dihydrate (CSD) precipitated on the surface of β-TCP granules and bridged β-TCP granules to one another. Increasing NaHSO4 concentration (from 0.5 mol/L to 5 mol/L) led to an increase in the amount of precipitant from 2.6 ± 0.2% to 21.6 ± 1.3% for DCPD and 1.3 ± 0.3% to 10.1 ± 0.5% for CSD. The diametral tensile strength was also increased from 0.03 ± 0.01 MPa to 2.0 ± 0.1 MPa with increasing NaHSO4 concentration. When 2 mol/L NaHSO4 solution was used as the liquid phase, setting time became 5.3 ± 0.2 min, which is suitable for handling in clinical applications to repair bone defects. In conclusion, β-TCP GC using NaHSO4 solution as the liquid phase has good potential value as bone augmentation cement.

Treatment of the benign lytic lesions of the proximal femur with synthetic bone graft

BackgroundBenign bone tumors and tumor-like conditions are commonly located in the proximal femur. The main indications for surgical treatment are lesions with impending or actual pathological fractures, or with aggressive or recurrent lesions. However, patients complaining of persistent pain, limping, or abnormal gait patterns are also considered for surgical treatment. In this study, we describe the outcomes of the surgical treatment of benign lytic lesions of the proximal femur by curettage followed by implantation of synthetic bone graft.MethodsThis retrospective study included 27 patients (22 females and 5 males) with benign lytic lesions of the proximal femur. The average age was 25.5 years (6–65 years), and the mean follow-up period was 54.5 months (9–145 months). The histopathological diagnoses were fibrous dysplasia (8 patients), simple bone cyst (8 patients), chondroblastoma (7 patients), giant cell tumor (3 patients), and eosinophilic granuloma (1 patient). These lesions were managed with curettage followed by implantation of the bone defects with alpha tricalcium phosphate in 14 patients, beta tricalcium phosphate granules in 11 patients, hydroxyapatite granules in 1 patient, and combined beta tricalcium phosphate and hydroxyapatite granules in 1 patient. Internal fixation was performed in three patients.ResultsThe mean operative time was 143 min (80–245 min). Patients had regained normal unrestricted activity without pain at the operation site. Patients treated with beta tricalcium phosphate achieved radiographic consolidation of the bone defects within 1 year after the surgery, and those treated with alpha tricalcium phosphate or hydroxyapatite experienced no progression nor recurrence of the lesions. Local tumor recurrence was observed in one patient with giant cell tumor 5 years after the surgery. Post-operative pathological fracture was occurred in one patient with a simple bone cyst of the subtrochanteric region 1 month after surgery. No post-operative infection was observed.ConclusionWe concluded that the treatment of benign lytic lesions of the proximal femur, either primary or recurrent, using synthetic bone graft is a safe and satisfactory method and the addition of internal fixation should be carefully planned.

Periodontal regeneration with autologous periodontal ligament-derived cell sheets - A safety and efficacy study in ten patients.

BackgroundPeriodontitis results in the destruction of tooth-supporting periodontal tissues and does not have the ability to heal spontaneously. Various approaches have been introduced to regenerate periodontal tissues; however, these approaches have limited efficacy for treating severe defects. Cytotherapies combine stem cell biology and tissue engineering to form a promising approach for overcoming these limitations. In this study, we isolated periodontal ligament (PDL)-derived cells from patients and created cell sheets with “Cell Sheet Engineering Technology”, using temperature responsive culture dishes, in which all the cultured cells can be harvested as an intact transplantable cell sheet by reducing the temperature of the culture dish. Subsequently, the safety and efficacy of autologous PDL-derived cell sheets were evaluated in a clinical setting.MethodsA single-arm and single-institute clinical study was performed to verify the safety and efficacy of autologous PDL-derived cell sheets in patients with periodontitis. Wisdom teeth were extracted from patients diagnosed with chronic periodontitis, ranging in age from 33 to 63 years (mean [±SD], 46 ± 12), and periodontal tissues were scraped for cell sources. Three-layered PDL-derived cell sheets were constructed using temperature-responsive culture dishes and transplanted in an autologous fashion following standard flap surgeries. Bony defects were filled with beta-tricalcium phosphate granules. Clinical variables were evaluated at baseline, 3 months, and 6 months. Cone-beam computed tomography was performed at baseline and 6 months. Additionally, mid-long-term follow-up has been performed with patients’ agreements.ResultsOur method was found to be safe and no severe adverse events were identified. All the findings, including reduction of periodontal probing depth (mean ± SD, 3.2 ± 1.9 mm), clinical attachment gain (2.5 ± 2.6 mm), and increase of radiographic bone height (2.3 ± 1.8 mm), were improved in all 10 cases at 6 months after the transplantation. These therapeutic effects were sustained during a mean follow-up period of 55 ± 19 months, and there were no serious adverse events.ConclusionsThe results of this study validate the safety and efficacy of autologous PDL-derived cell sheets in severe periodontal defects, and the stability of this efficacy during mid-long-term follow up. This cytotherapeutic approach, based on cell sheet engineering, offers an innovative strategy to treat the recognized unmet need of treating severe periodontal defects.

Evaluation of an In Situ Hardening β-Tricalcium Phosphate Graft Material for Alveolar Ridge Preservation. A Histomorphometric Animal Study in Pigs.

The purpose of this study was to investigate the effectiveness of a resorbable alloplastic in situ hardening bone grafting material for alveolar ridge preservation in a swine model. Seven Landrace pigs were used. In each animal, the maxillary left and right deciduous second molars were extracted, and extraction sites were either grafted with a resorbable alloplastic in situ hardening bone substitute, composed of beta-tricalcium phosphate (β-TCP) granules coated with poly(lactic-co-glycolic) acid (PLGA), or left unfilled to heal spontaneously. Animals were euthanized after 12 weeks, and the bone tissue was analyzed histologically and histomorphometrically. Linear changes of ridge width were also clinically measured and analyzed. Pronounced bone regeneration was found in both experimental and control sites, with no statistically significant differences. At the experimental sites, most of the alloplastic grafting material was resorbed and remnants of the graft particles were severely decreased in size. Moreover, experimental sites showed, in a statistically nonsignificant way, less mean horizontal dimensional reduction of the alveolar ridge (7.69%) compared to the control sites (8.86%). In conclusion, the β-TCP/PLGA biomaterial performed well as a biocompatible resorbable in situ hardening bone substitute when placed in intact extraction sockets in this animal model.

A novel cytotherapy device for rapid screening, enriching and combining mesenchymal stem cells into a biomaterial for promoting bone regeneration

Bone defects are a common challenge in clinic, usually warranting bone grafts. However, current strategies to obtain effective graft materials have many drawbacks. Mesenchymal stem cell (MSC)-based therapy is a promising alternative. We designed an innovative appliance named the stem cell screen–enrich–combine(-biomaterials) circulating system (SECCS). In this study, 42 patients who required bone graft underwent SECCS-based treatment. Their bone marrow samples and beta-tricalcium phosphate (β-TCP) granules were processed in the SECCS for 10–15 minutes, to produce MSC/β-TCP composites. These composites were grafted back into bone defect sites. The results showed 85.53% ± 7.95% autologous MSCs were successfully screened, enriched, and seeded on the β-TCP scaffolds synchronously. The cell viability remained unchanged after SECCS processing. Clinically, all patients obtained satisfactory bone healing. Thus, without in vitro culture, the SECCS can produce bioactive MSC/β-TCP composites for bone regeneration during surgery. The SECCS represents a convenient, rapid, low-cost, and safe method for bone regeneration.

Bone Marrow Mononuclear Cells Combined with Beta-Tricalcium Phosphate Granules for Alveolar Cleft Repair: A 12-Month Clinical Study

Alveolar cleft is the most common congenital bone defect. Autologous iliac crest bone graft (ICBG) is the most widely adopted procedure for alveolar cleft repair, but the condition is associated with door-site morbidities. For the first time, this study used bone marrow mononuclear cells (BMMNCs) combined with beta-tricalcium phosphate (β-TCP) granules to repair alveolar bone defect. The effectiveness of this technique was compared with autologous ICBG after 12 months of follow-up. The bone formation volume was quantitatively evaluated by three-dimensional computed tomography and computer aided engineering technology. BMMNCs/β-TCP granule grafting was radiographically equivalent to ICBG in alveolar cleft repair. Although considerable resorption was observed up to 6 months after surgery, no significant differences were noted in the Chelsea score and bone formation volume between groups. These finding indicate that BMMNCs/β-TCP grafting is a safe and effective approach for alveolar bone regeneration.

Cranioplasty with Adipose-Derived Stem Cells, Beta-Tricalcium Phosphate Granules and Supporting Mesh: Six-Year Clinical Follow-Up Results.

Several alternative techniques exist to reconstruct skull defects. The complication rate of the cranioplasty procedure is high and the search for optimal materials and techniques continues. To report long‐term results of patients who have received a cranioplasty using autologous adipose‐derived stem cells (ASCs) seeded on beta‐tricalcium phosphate (betaTCP) granules. Between 10/2008 and 3/2010, five cranioplasties were performed (four females, one male; average age 62.0 years) using ASCs, betaTCP granules and titanium or resorbable meshes. The average defect size was 8.1 × 6.7 cm2. Patients were followed both clinically and radiologically. The initial results were promising, with no serious complications. Nevertheless, in the long‐term follow‐up, three of the five patients were re‐operated due to graft related problems. Two patients showed marked resorption of the graft, which led to revision surgery. One patient developed a late infection (7.3 years post‐operative) that required revision surgery and removal of the graft. One patient had a successfully ossified graft, but was re‐operated due to recurrence of the meningioma 2.2 years post‐operatively. One patient had an uneventful clinical follow‐up, and the cosmetic result is satisfactory, even though skull x‐rays show hypodensity in the borders of the graft. Albeit no serious adverse events occurred, the 6‐year follow‐up results of the five cases are unsatisfactory. The clinical results are not superior to results achieved by conventional cranial repair methods. The use of stem cells in combination with betaTCP granules and supporting meshes in cranial defect reconstruction need to be studied further before continuing with clinical trials. Stem Cells Translational Medicine 2017;6:1576–1582

Biocompatibility, resorption and biofunctionality of a new synthetic biodegradable membrane for guided bone regeneration

Membranes for guided bone regeneration (GBR) were prepared from the synthetic biodegradable polymer poly-D,L-lactic/glycolic acid (PLGA). This GBR membrane has a bi-layered structure with a dense film to prevent gingival fibroblast ingrowth and ensure mechanical function, and a micro-fibrous layer to support colonization by osteogenic cells and promote bone regeneration. Hydrolysis and biodegradation were both studied in vitro through soaking in phosphate buffered saline (PBS) and in vivo by implantation in the subcutis of rats for 4, 8, 16, 26, 48 and 52 weeks. Histology revealed an excellent colonization of the micro-fibrous layer by cells with a minimal inflammatory reaction during resorption. GBR using the synthetic PLGA membrane was evaluated on critical-size calvaria defects in rats for 4 and 8 weeks. Radiographs, micro-computed tomography and histology showed bone regeneration with the PLGA membrane, while the defects covered with a collagen membrane showed a limited amount of mineralized bone, similar to that of the defect left empty. The biofunctionality of the PLGA membranes was also compared to collagen membranes in mandible defects in rabbits, associated or not with beta-tricalcium phosphate granules. This study revealed that the bi-layered synthetic membrane made of PLGA was safer, more biocompatible, and had a greater controlled resorption rate and bone regeneration capacity than collagen membranes. This new PLGA membrane could be used in pre-implantology and peri-odontology surgery.

In Vitro Biocompatibility Assessment and In Vivo Behavior of a New Osteoconductive βTCP Bone Substitute

Beta-tricalcium phosphate (βTCP) granules (OsproLife) exhibit a pure crystalline phase and a rough microporous surface for promoting cell adhesion and microsized intragranule porosity for improving wettability and resorption necessary for bone regeneration. OsproLife is a fully resorbable, space-maintaining, and osteoconductive synthetic material for the filling of bone defects. To asses OsproLife properties, a similar synthetic biomaterial, already on the market, has been chosen as reference: Cerasorb has the same chemical composition, but different crystal structure, surface morphology, and granule size. The aim of this study is to compare the properties of OsproLife and Cerasorb. Chemical purity, composition and physical properties, in vitro cytotoxicity, and in vivo bone performance in a rabbit model were analyzed. βTCP OsproLife granules (test) were compared with Cerasorb (control). Histological and μCT analyses were performed at 6, 12, and 56 weeks after implantation. βTCP OsproLife and Cerasorb granules result to be both biocompatible and characterized by the same osteoconductivity and resorption rate. βTCP OsproLife granules are a promising bone substitute for dental and orthopedic applications.

Purmorphamine increased adhesion, proliferation and expression of osteoblast phenotype markers of human dental pulp stem cells cultured on beta-tricalcium phosphate.

Growth factors play a significant role in cell proliferation and differentiation during different stages of the bone repair. However, several limitations have been brought researchers attention to an osteoinductive small molecule including Purmorphamine. In this study, we aimed to evaluate the effect of Purmorphamine on adhesion, proliferation and differentiation of human dental pulp stem cells (hDPSCs) seaded on beta-tricalcium phosphate (β-TCP) granules. hDPSCs were established from extracted wisdom teeth of healthy volenteers. Cells at passage 3 were seeded on β-TCP in the presence or absence of Purmorphamine. Cell adhesion and proliferation were assessed using scanning electeron microscopy (SEM) and DNA counting assay, respectively, after 1, 3 and 5days. Then, hDPSCs seeded on β-TCP were subjected to osteogenic medium with or without Purmorphamine. After 7 and 14days osteogenic diffrentiation capability of hDPSCs were determined using real-time RT-PCR and alkaline phosphatase (ALP) activity assay. The significant increase in amount of DNA was observed at day 3 and 5 in the presence of Purmorphamine. SEM imaging also was confirmed the DNA counting assay; in all given time points, hDPSC attachment and growth was significantly higher in the presence of Purmorphamine. ALP activity was increased by Purmorphamine at both 7 and 14days of induction. Purmorphamine showed to effect on osteopontin expression at earlier stage of osteogenic differentiation, whereas for osteocalcin expression, this effect was more evident at later stage of differentiation. Purmorphamine had a promotive effect on adhesion, proliferation and osteogenic differentiation of hDPSCs cultured on β-TCP. The outcome of the current study would help in development of in vitro culture conditions for better osteogenic differentiation of hDPSCs prior to transplantation.

Beta-tricalcium phosphate granules improve osteogenesis in vitro and establish innovative osteo-regenerators for bone tissue engineering in vivo.

The drawbacks of traditional bone-defect treatments have prompted the exploration of bone tissue engineering. This study aimed to explore suitable β-tricalcium phosphate (β-TCP) granules for bone regeneration and identify an efficient method to establish β-TCP-based osteo-regenerators. β-TCP granules with diameters of 1 mm and 1–2.5 mm were evaluated in vitro. The β-TCP granules with superior osteogenic properties were used to establish in vivo bioreactors, referred to as osteo-regenerators, which were fabricated using two different methods. Improved proliferation of bone mesenchymal stem cells (BMSCs), glucose consumption and ALP activity were observed for 1–2.5 mm β-TCP compared with 1-mm granules (P < 0.05). In addition, BMSCs incubated with 1–2.5 mm β-TCP expressed significantly higher levels of the genes for runt-related transcription factor-2, alkaline phosphatase, osteocalcin, osteopontin, and collagen type-1 and the osteogenesis-related proteins alkaline phosphatase, collagen type-1 and runt-related transcription factor-2 compared with BMSCs incubated with 1 mm β-TCP (P < 0.05). Fluorochrome labelling, micro-computed tomography and histological staining analyses indicated that the osteo-regenerator with two holes perforating the femur promoted significantly greater bone regeneration compared with the osteo-regenerator with a periosteum incision (P < 0.05). This study provides an alternative to biofunctionalized bioreactors that exhibits improved osteogenesis.

Minimally Invasive Alveolar Ridge Preservation Utilizing an In Situ Hardening β-Tricalcium Phosphate Bone Substitute: A Multicenter Case Series.

Ridge preservation measures, which include the filling of extraction sockets with bone substitutes, have been shown to reduce ridge resorption, while methods that do not require primary soft tissue closure minimize patient morbidity and decrease surgical time and cost. In a case series of 10 patients requiring single extraction, in situ hardening beta-tricalcium phosphate (β-TCP) granules coated with poly(lactic-co-glycolic acid) (PLGA) were utilized as a grafting material that does not necessitate primary wound closure. After 4 months, clinical observations revealed excellent soft tissue healing without loss of attached gingiva in all cases. At reentry for implant placement, bone core biopsies were obtained and primary implant stability was measured by final seating torque and resonance frequency analysis. Histological and histomorphometrical analysis revealed pronounced bone regeneration (24.4 ± 7.9% new bone) in parallel to the resorption of the grafting material (12.9 ± 7.7% graft material) while high levels of primary implant stability were recorded. Within the limits of this case series, the results suggest that β-TCP coated with polylactide can support new bone formation at postextraction sockets, while the properties of the material improve the handling and produce a stable and porous bone substitute scaffold in situ, facilitating the application of noninvasive surgical techniques.

Regulation and Biological Significance of Formation of Osteoclasts and Foreign Body Giant Cells in an Extraskeletal Implantation Model.

The implantation of biomaterials induces a granulomatous reaction accompanied by foreign body giant cells (FBGCs). The characterization of multinucleated giant cells (MNGCs) around bone substitutes implanted in bone defects is more complicated because of healing with bone admixed with residual bone substitutes and their hybrid, and the appearance of two kinds of MNGCs, osteoclasts and FBGCs. Furthermore, the clinical significance of osteoclasts and FBGCs in the healing of implanted regions remains unclear. The aim of the present study was to characterize MNGCs around bone substitutes using an extraskeletal implantation model and evaluate the clinical significance of osteoclasts and FBGCs. Beta-tricalcium phosphate (β-TCP) granules were implanted into rat subcutaneous tissue with or without bone marrow mesenchymal cells (BMMCs), which include osteogenic progenitor cells. We also compared the biological significance of plasma and purified fibrin, which were used as binders for implants. Twelve weeks after implantation, osteogenesis was only detected in specimens implanted with BMMCs. The expression of two typical osteoclast markers, tartrate-resistant acid phosphatase (TRAP) and cathepsin-K (CTSK), was analyzed, and TRAP-positive and CTSK-positive osteoclasts were only detected beside bone. In contrast, most of the MNGCs in specimens without the implantation of BMMCs were FBGCs that were negative for TRAP, whereas the degradation of β-TCP was detected. In the region implanted with β-TCP granules with plasma, FBGCs tested positive for CTSK, and when β-TCP granules were implanted with purified fibrin, FBGCs tested negative for CTSK. These results showed that osteogenesis was essential to osteoclastogenesis, two kinds of FBGCs, CTSK-positive and CTSK-negative, were induced, and the expression of CTSK was plasma-dependent. In addition, the implantation of BMMCs was suggested to contribute to osteogenesis and the replacement of implanted β-TCP granules to bone.

β-TCP granules mixed with reticulated hyaluronic acid induce an increase in bone apposition

β beta-tricalcium phosphate (β-TCP) granules are suitable for repair of bone defects. They have an osteoconductive effect shortly after implantation. However, dry granules are difficult to handle in the surgical room because of low weight and lack of cohesion. Incorporation of granules in a hydrogel could be a satisfactory solution. We have investigated the use of hyaluronic acid (HyA) as an aqueous binder of the granules. β-TCP granules were prepared by the polyurethane foam technology. Commercially available linear (LHya) and reticulated hyaluronic acid (RHyA) in aqueous solution were used to prepare a pasty mixture that can be handled more easily than granules alone. Thirteen New Zealand White rabbits (3.5–3.75 kg) were used; a 4 mm hole was drilled in each femoral condyle. After flushing, holes were filled with either LHyA, RHyA, dry β-TCP granules alone, β-TCP granules + LHyA and β-TCP granules + RHyA. Rabbits were allowed to heal for one month, sacrificed and femurs were harvested and analysed by microCT and histomorphometry. The net amount of newly formed bone was derived from measurements done after thresholding the microCT images for the material and for the material+bone. LHyA and RHyA did not result in healing of the grafted area. LHyA was rapidly eluted from the grafted zone but allowed deposition of more granules, although the amount of formed bone was not significantly higher than with β-TCP granules alone. RHyA permitted the deposition of more granules which induced significantly more bone trabeculae without inducing an inflammatory reaction. RHyA appears to be a good vehicle to implant granules of β-TCP, since HyA does not interfere with bone remodeling.