Local administration of HMGB-1 promotes bone regeneration on the critical-sized mandibular defects in rabbits.

Reconstruction of a critical-sized osseous defect is challenging in maxillofacial surgery. Despite novel treatments and advances in supportive therapies, severe complications including infection, nonunion, and malunion can still occur. Here, we aimed to assess the use of a beta-tricalcium phosphate (ß-TCP) scaffold loaded with high mobility group box-1 protein (HMGB-1) as a novel critical-sized bone defect treatment in rabbits. The study was performed on 15 specific pathogen-free New Zealand rabbits divided into three groups: Group A had an osseous defect filled with a ß-TCP scaffold loaded with phosphate-buffered saline (PBS) (100 µL/scaffold), the defect in group B was filled with recombinant human bone morphogenetic protein 2 (rhBMP-2) (10 µg/100 µL), and the defect in group C was loaded with HMGB-1 (10 µg/100 µL). Micro-computed tomography (CT) examination demonstrated that group C (HMGB-1) showed the highest new bone volume ratio, with a mean value of 66.5%, followed by the group B (rhBMP-2) (31.0%), and group A (Control) (7.1%). Histological examination of the HMGB-1 treated group showed a vast area covered by lamellar and woven bone surrounding the ß-TCP granule remnants. These results suggest that HMGB-1 could be an effective alternative molecule for bone regeneration in critical-sized mandibular bone defects.

Fractura patológica mandibular bilateral en osteonecrosis maxilar inducida por bisfosfonatos / Bilateral pathologic mandibular fracture in maxillary osteonecrosis induced by bisphosphonates

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Skeletal Stem Cell-Schwann Cell Circuitry in Mandibular Repair.

Regenerative paradigms exhibit nerve dependency, including regeneration of the mouse digit tip and salamander limb. Denervation impairs regeneration and produces morphological aberrancy in these contexts, but the direct effect of innervation on the stem and progenitor cells enacting these processes is unknown. We devised a model to examine nerve dependency of the mouse skeletal stem cell (mSSC), the progenitor responsible for skeletal development and repair. We show that after inferior alveolar denervation, mandibular bone repair is compromised because of functional defects in mSSCs. We present mSSC reliance on paracrine factors secreted by Schwann cells as the underlying mechanism, with partial rescue of the denervated phenotype by Schwann cell transplantation and by Schwann-derived growth factors. This work sheds light on the nerve dependency of mSSCs and has implications for clinical treatment of mandibular defects.

Localized low-dose rhBMP-2 is effective at promoting bone regeneration in mandibular segmental defects.

At least 26% of recent battlefield injuries are to the craniomaxillofacial (CMF) region. Recombinant human bone morphogenetic protein 2 (rhBMP-2) is used to treat CMF open fractures, but several complications have been associated with its use. This study tested the efficacy and safety of a lower (30% recommended) dose of rhBMP-2 to treat mandibular fractures. rhBMP-2 delivered via a polyurethane (PUR) and hydroxyapatite/ß-tricalcium phosphate (Mastergraft®) scaffold was evaluated in a 2 cm segmental mandibular defect in minipigs. Bone regeneration was analyzed at 4, 8, and 12 weeks postsurgery using clinical computed tomography (CT) and rhBMP-2, and inflammatory marker concentrations were analyzed in serum and surgery-site drain effluent. CT scans revealed that pigs treated with PUR-Mastergraft® + rhBMP-2 had complete bone bridging, while the negative control group showed incomplete bone-bridging (n = 6). Volumetric analysis of regenerated bone showed that the PUR-Mastergraft® + rhBMP-2 treatment generated significantly more bone than control by 4 weeks, a trend that continued through 12 weeks. Variations in inflammatory analytes were detected in drain effluent samples and saliva but not in serum, suggesting a localized healing response. Importantly, the rhBMP-2 group did not exhibit an excessive increase in inflammatory analytes compared to control. Treatment with low-dose rhBMP-2 increases bone regeneration capacity in pigs with mandibular continuity defects and restores bone quality. Negative complications from rhBMP-2, such as excessive inflammatory analyte levels, were not observed. Together, these results suggest that treatment with low-dose rhBMP-2 is efficacious and may improve safety when treating CMF open fractures. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1491-1503, 2019.

Small molecule-mediated tribbles homolog 3 promotes bone formation induced by bone morphogenetic protein-2.

Although bone morphogenetic protein-2 (BMP2) has demonstrated extraordinary potential in bone formation, its clinical applications require supraphysiological milligram-level doses that increase postoperative inflammation and inappropriate adipogenesis, resulting in well-documented life-threatening cervical swelling and cyst-like bone formation. Recent promising alternative biomolecular strategies are toward promoting pro-osteogenic activity of BMP2 while simultaneously suppressing its adverse effects. Here, we demonstrated that small molecular phenamil synergized osteogenesis and bone formation with BMP2 in a rat critical size mandibular defect model. Moreover, we successfully elicited the BMP2 adverse outcomes (i.e. adipogenesis and inflammation) in the mandibular defect by applying high dose BMP2. Phenamil treatment significantly improves the quality of newly formed bone by inhibiting BMP2 induced fatty cyst-like structure and inflammatory soft-tissue swelling. The observed positive phenamil effects were associated with upregulation of tribbles homolog 3 (Trib3) that suppressed adipogenic differentiation and inflammatory responses by negatively regulating PPARγ and NF-κB transcriptional activities. Thus, use of BMP2 along with phenamil stimulation or Trib3 augmentation may be a promising strategy to improve clinical efficacy and safety of current BMP therapeutics.

Enhanced Mandibular Bone Repair by Combined Treatment of Bone Morphogenetic Protein 2 and Small-Molecule Phenamil.

Growth factor-based therapeutics using bone morphogenetic protein 2 (BMP-2) presents a promising strategy to reconstruct craniofacial bone defects such as mandible. However, clinical applications require supraphysiological BMP doses that often increase inappropriate adipogenesis, resulting in well-documented, cyst-like bone formation. Here we reported a novel complementary strategy to enhance osteogenesis and mandibular bone repair by using small-molecule phenamil that has been shown to be a strong activator of BMP signaling. Phenamil synergistically induced osteogenic differentiation of human bone marrow mesenchymal stem cells with BMP-2 while suppressing their adipogenic differentiation induced by BMP-2 in vitro. The observed pro-osteogenic and antiadipogenic activity of phenamil was mediated by expression of tribbles homolog 3 (Trb3) that enhanced BMP-smad signaling and inhibited expression of peroxisome proliferator-activated receptor gamma (PPARγ), a master regulator of adipogenesis. The synergistic effect of BMP-2+phenamil on bone regeneration was further confirmed in a critical-sized rat mandibular bone defect by implanting polymer scaffolds designed to slowly release the therapeutic molecules. These findings indicate a new complementary osteoinductive strategy to improve clinical efficacy and safety of current BMP-based therapeutics.

Octacalcium phosphate collagen composite facilitates bone regeneration of large mandibular bone defect in humans.

Recently it was reported that the implantation of octacalcium phosphate (OCP) and collagen composite (OCP-collagen) was effective at promoting bone healing in small bone defects after cystectomy in humans. In addition, OCP-collagen promoted bone regeneration in a critical-sized bone defect of a rodent or canine model. In this study, OCP-collagen was implanted into a human mandibular bone defect with a longer axis of approximately 40 mm, which was diagnosed as a residual cyst with apical periodontitis. The amount of OCP-collagen implanted was about five times greater than the amounts implanted in previous clinical cases. Postoperative wound healing was satisfactory and no infection or allergic reactions occurred. The OCP-collagen-treated lesion was gradually filled with radio-opaque figures, and the alveolar region occupied the whole of the bone defect 12 months after implantation. This study suggests that OCP-collagen could be a useful bone substitute material for repairing large bone defects in humans that might not heal spontaneously. Copyright © 2015 John Wiley & Sons, Ltd.

Sustained, localized salicylic acid delivery enhances diabetic bone regeneration via prolonged mitigation of inflammation.

Diabetes is a metabolic disorder caused by insulin resistance and/or deficiency and impairs bone quality and bone healing due to altered gene expression, reduced vascularization, and prolonged inflammation. No effective treatments for diabetic bone healing are currently available, and most existing treatments do not directly address the diabetic complications that impair bone healing. We recently demonstrated that sustained and localized delivery of salicylic acid (SA) via an SA-based polymer provides a low-cost approach to enhance diabetic bone regeneration. Herein, we report mechanistic studies that delve into the biological action and local pharmacokinetics of SA-releasing polymers shown to enhance diabetic bone regeneration. The results suggest that low SA concentrations were locally maintained at the bone defect site for more than 1 month. As a result of the sustained SA release, a significantly reduced inflammation was observed in diabetic animals, which in turn, yielded reduced osteoclast density and activity, as well as increased osteoblastogenesis. Based upon these results, localized and sustained SA delivery from the SA-based polymer effectively improved bone regeneration in diabetic animals by affecting both osteoclasts and osteoblasts, thereby providing a positive basis for clinical treatments. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2595-2603, 2016.

Local administration of stromal cell-derived factor-1 promotes stem cell recruitment and bone regeneration in a rat periodontal bone defect model.

Stromal cell-derived factor-1 (SDF-1) recruits adult stem/progenitor cells via its specific receptor, C-X-C motif receptor 4 (CXCR4), to promote heart, kidney and tendon regeneration, but little is known about the effects of SDF-1 on bone regeneration in periodontal diseases. The objective of this study was to investigate whether local administration of SDF-1 in a collagen membrane scaffold enhanced the recruitment of host stem cells and improved periodontal bone defect repair. To this end, bone defects were established on the buccal side of bilateral mandibles in Wistar rats. After application of collagen membranes loaded with SDF-1 or phosphate-buffered saline (PBS) to the defects, the effects of SDF-1 on stem cell recruitment, inflammatory cell responses, angiogenesis, osteoclastogenesis, scaffold degradation, and bone regeneration were evaluated. It showed that SDF-1 recruited host-derived mesenchymal stem cells and hematopoietic stem cells to the wound area and significantly reduced the CD11b+ inflammatory cell response. Moreover, SDF-1 increased vascular formation, induced early bone osteoclastogenesis, accelerated scaffold degradation, and promoted the quality and quantity of regenerated bone. Our results suggest that this cell-free approach by local administration of SDF-1 may be an effective strategy for development as a simple and safe technique for periodontal bone regeneration.

Angiogenesis and bone regeneration of porous nano-hydroxyapatite/coralline blocks coated with rhVEGF165 in critical-size alveolar bone defects in vivo.

To improve the regenerative performance of nano-hydroxyapatite/coralline (nHA/coral) block grafting in a canine mandibular critical-size defect model, nHA/coral blocks were coated with recombinant human vascular endothelial growth factor(165) (rhVEGF) via physical adsorption (3 µg rhVEGF165 per nHA/coral block). After the nHA/coral blocks and VEGF/nHA/coral blocks were randomly implanted into the mandibular box-shaped defects in a split-mouth design, the healing process was evaluated by histological observation and histomorphometric and immunohistological analyses. The histological evaluations revealed the ingrowth of newly formed blood vessels and bone at the periphery and cores of the blocks in both groups at both 3 and 8 weeks postsurgery, respectively. In the histomorphometric analysis, the VEGF/nHA/coral group exhibited a larger quantity of new bone formation at 3 and 8 weeks postsurgery. The percentages of newly formed bone within the entire blocks in the VEGF/nHA/coral group were 27.3% ± 8.1% and 39.3% ± 12.8% at 3 weeks and 8 weeks, respectively, and these values were slightly greater than those of the nHA/coral group (21.7% ± 3.0% and 32.6% ± 10.3%, respectively), but the differences were not significant (P>0.05). The immunohistological evaluations revealed that the neovascular density in the VEGF/nHA/coral group (146 ± 32.9 vessel/mm(2)) was much greater than that in the nHA/coral group (105 ± 51.8 vessel/mm(2)) at the 3-week time point (P<0.05), but no significant difference was observed at the 8-week time point (341 ± 86.1 and 269 ± 50.7 vessel/mm(2), respectively, P>0.05). The present study indicated that nHA/coral blocks might be optimal scaffolds for block grafting in critical-size mandibular defects and that additional VEGF coating via physical adsorption can promote angiogenesis in the early stage of bone healing, which suggests that prevascularized nHA/coral blocks have significant potential as a bioactive material for bone regeneration in large-scale alveolar defects.

Osseous wound repair under inhibition of the axis of advanced glycation end-products and the advanced glycation end-products receptor.

BACKGROUND/PURPOSE: Blockade of advanced glycation end-products (AGE) is able to reduce diabetic complications and control periodontitis. This study aimed to determine whether the application of aminoguanidine (AG), an AGE inhibitor, or N-phenacylthiazolium bromide (PTB), an AGE breaker, facilitates the healing of an osseous wound in non-diabetic animals. METHODS: 2.6 mm diameter full-thickness osseous wounds were created bilaterally in 54 healthy Sprague-Dawley rats. Rats received daily normal saline, AG, or PTB injections respectively and were euthanized after 7 days, 14 days, or 28 days (n = 6). The wound healing pattern was assessed by micro-computed tomography, histology, histochemistry for the fiber arrangement, and the gene expression levels of AGE receptor, tumor necrosis factor-α, type I collagen, and fibronectin. RESULTS: Under the AG and PTB administration, osteogenesis was apparently promoted in the early stages of healing, but the union of the osseous wound and the fibril re-arrangement was apparently retarded. No significant difference was found in any of the micro-computed tomography parameters as compared to the control in the first 14 days, whereas the relative bone volume was significantly higher in the control at Day 28. AGE receptor and tumor necrosis factor-α were depressed in the PTB group, but only temporarily at Day 14 in the AG group. Therefore, at Day 14, type I collagen was significantly upregulated in the PTB group, and fibronectin was significantly increased in the AG group. CONCLUSION: Anti-AGE agents reduced inflammation but did not apparently facilitate osteogenesis during the osseous wound repair.

Delivery of growth factors using a smart porous nanocomposite scaffold to repair a mandibular bone defect.

Implantation of a porous scaffold with a large volume into the body in a convenient and safe manner is still a challenging task in the repair of bone defects. In this study, we present a porous smart nanocomposite scaffold with a combination of shape memory function and controlled delivery of growth factors. The shape memory function enables the scaffold with a large volume to be deformed into its temporal architecture with a small volume using hot-compression and can subsequently recover its original shape upon exposure to body temperature after it is implanted in the body. The scaffold consists of chemically cross-linked poly(ε-caprolactone) (c-PCL) and hydroxyapatite nanoparticles. The highly interconnected pores of the scaffold were obtained using the sugar leaching method. The shape memory porous scaffold loaded with bone morphogenetic protein-2 (BMP-2) was also fabricated by coating the calcium alginate layer and BMP-2 on the surface of the pore wall. Under both in vitro and in vivo environmental conditions, the porous scaffold displays good shape memory recovery from the compressed shape with deformed pores of 33 µm in diameter to recover its porous shape with original pores of 160 µm in diameter. In vitro cytotoxicity based on the MTT test revealed that the scaffold exhibited good cytocompatibility. The in vivo micro-CT and histomorphometry results demonstrated that the porous scaffold could promote new bone generation in the rabbit mandibular bone defect. Thus, our results indicated that this shape memory porous scaffold demonstrated great potential for application in bone regenerative medicine.

[Stages of bone regeneration and foundation of pharmacоlogical correction of the mandible reparative osteogenesis].

Influents of some medicines on the mandible reparative regeneration in experimental investigations are present in the manuscript. It was discovered that application of parathyroid hormone (PTG) in first 3 days after the mandible fracture decreases of quantity complications on 30% and contributes strong consolidation of bone fragments. Metiluracil in the same period increases complications quantity on 36% and bone fragments consolidation strength was for sure less than after PTG. It was found PTG and vitamin D3 in first resorbtion stage accelerate bone consolidation, retabolil (nandrolone), dexametasone, testosterone and vitamin E slow down bone consolidation. Role of vitamin A, indometazin and calcitonin was doubtful. Practical doctors and experimenters co-ordination efforts are necessary for elaboration of new tactic and strategy of patient treatment with bone trauma.

Análise histológica da lesão óssea de mandíbula de coelho após aplicação local de cloreto de estrôncio / Histological analysis of surgically injured rabbit mandibles treated topically with strontium chloride

OBJETIVO: Avaliar, pela histologia, o efeito da aplicação tópica do cloreto de estrôncio em defeitos ósseos provocados na mandíbula de coelho. MÉTODOS: Foram utilizados 12 coelhos (New Zealand), nos quais se produziram dois defeitos cirúrgicos nas regiões laterais da mandíbula, bilateralmente. Logo após, os defeitos cirúrgicos do lado direito foram preenchidos com esponja de colágeno embebida em soro fisiológico (Controle) e os do lado esquerdo preenchidos com o mesmo material embebido em solução de cloreto de estrôncio a 2 Molar (Experimento). Os animais foram divididos em dois grupos e eutanasiados após 28 e 56 dias. O material coletado foi incluído para processamento histológico de rotina e as lâminas coradas pela hematoxilina e eosina (H.E.). RESULTADOS: A aplicação tópica de cloreto de estrôncio estimulou e acelerou a neoformação óssea nos defeitos cirúrgicos, tratados com cloreto de estrôncio (28 dias) quando se fez comparação entre os dois grupos. Aos 28 dias o osso neoformado foi predominantemente primário. Aos 56 dias a neoformação óssea preencheu totalmente os defeitos cirúrgicos, tanto do grupo onde se utilizou a solução fisiológica quanto do tratado com cloreto de estrôncio. No entanto, notou-se que nos coelhos tratados com estrôncio o tecido ósseo neoformado se apresentou mais desenvolvido, mostrando a presença de sistemas de Havers. CONCLUSÃO: A aplicação tópica de cloreto de estrôncio estimula e acelera a reparação óssea em lesão, provocada artificialmente em mandíbula de coelho quando se compararam os dois grupos (controle x experimento).

OBJECTIVE: This study histologically assessed the effect of applying strontium chloride topically to surgically-induced bone defects in rabbit mandibles. METHODS: Small holes were made surgically on both sides of the lateral region of the mandible of 12 New Zealand rabbits. The holes on the right side were then filled with a collagen sponge soaked in saline (control) and the holes on the left were filled with a collagen sponge soaked in a 2 molar solution of strontium chloride. The animals were divided into two groups: the control group or GI was killed 28 days later and the experimental group or GII was killed 56 days later. The material was included for routine histological processing and the slices were stained with hematoxylin and eosin (HE). RESULTS: At 28 days, the topical application of strontium chloride had stimulated and accelerated new bone formation in the surgically-induced bone defects. At this time, the newly formed bone was mostly primary. At 56 days, newly formed bone had completely filled both the holes treated with saline and strontium chloride. However, the newly formed bone in the holes treated with strontium chloride was more developed, presenting several Haversian systems. CONCLUSION: Topical application of strontium chloride stimulates and accelerates the repair of surgically-induced bone defects in rabbit mandibles.

Antibiotic-containing collagen for the treatment of bone defects.

Recent studies have explored the use of biodegradable implants that incorporate antibiotics for the treatment of bone infections. In this study, a biodegradable composite containing bovine collagen and teicoplanin (Targobone) was used for the treatment of mandibular nonunion defects. Patients with mandibular nonunion defects subsequent to osteosynthesis were treated with Targobone (n = 9) or with autologous bone grafts (n = 12). Clinical and radiological evaluations were performed preoperatively, immediately postoperatively, and 4 and 24 weeks postoperatively. Bone regeneration was defined relative to the original defect area in the panoramic radiograph by using image analysis software. In the Targobone group, the defect area decreased to 78% (SD +/- 21.8%) of the preoperative area within 4 weeks and to 21% (SD +/- 9.7%) of the preoperative area within 24 weeks. In the autologous bone graft group, the defect area decreased to 69% (SD +/- 32.4%) of the preoperative area within 4 weeks and to 4.7% (SD +/- 5.6%) of the preoperative area within 24 weeks. Thus, Targobone is a promising option for the treatment of bone defects.

Defect repair in the rat mandible with bone morphogenic protein 5 and prostaglandin E1.

OBJECTIVE: To compare the osteogenic abilities of 2 growth factors (bone morphogenic protein 5 [BMP-5] and prostaglandin E1 [PGE1]) and 2 carriers (collagen/polylactic acid [PLA] and collagen/calcium hydroxyapatite cement [HAC]) in the repair of a rat mandibular body defect. DESIGN: Prospective controlled trial. Subjects Twenty-nine Sprague-Dawley rats. INTERVENTIONS: Critical size defects were created in the bilateral mandibular bodies of the rats. Each hemimandible was assigned to an experimental group. The defects were filled with PLA (group 1), PLA with BMP-5 (group 2), PLA with PGE1 (group 3), HAC (group 4), HAC with BMP-5 (group 5), or HAC with PGE1 (group 6). The control group (group 7) had unfilled defects. The animals were killed after 12 weeks, and the nondemineralized specimens were processed histologically. Stereologic techniques were used to determine the volume fractions of new bone, osteoid, marrow, remaining implant, and fibrous tissue in each defect. RESULTS: The HAC/BMP-5 group (group 5) contained significantly more new bone than the PLA/BMP-5 group (group 2) (P =.02), the HAC and HAC/PGE1 groups (groups 4 and 6) (P =.002), and the control group (group 7) (P<.01). The HAC/BMP-5 group also had less fibrous tissue than the HAC group and the HAC/PGE1 group (P<.001). Groups 5 and 6 had less fibrous tissue than group 7 (P<.01). The groups containing PGE1 demonstrated significantly more osteoid development than the other experimental groups (P<.001). CONCLUSIONS: Inclusion of BMP-5 in an implant with calcium hydroxyapatite cement resulted in the formation of significantly larger fractions of new bone and less fibrous tissue ingrowth than occurred in the other experimental groups. The presence of PGE1 resulted in larger amounts of osteoid deposition, suggesting the potential for delayed bone healing.

Effects of recombinant human fibroblast growth factor-2 on osteogenic cell populations during orthopic osteogenesis in vivo.

The osteogenic effects of fibroblast growth factor-2 (FGF-2) in vivo on different cell populations of the osteoblastic cell lineage have not been fully elucidated. In this study, the efficacy of recombinant human fibroblast growth factor-2 (rhFGF-2) to stimulate orthopic bone formation in transosseous rat mandibular defects, with different cell populations allowed access to the defects, was investigated with the aim to further decipher FGF-2 effects. Three different doses of rhFGF-2 (10 ng, 100 ng, and 1 microg) were delivered in an absorbable collagen sponge carrier, whereas some defects were implanted with the carrier only, and some were left untreated. Barrier membranes, made of microporous expanded polytetrafluoroethylene, were simultaneously placed over half the number of defects in each treatment group, thus forcing osteogenic cells to be derived from intraosseous sources. Evaluation was made by light microscopy and computerized image analysis after 12 and 24 of days healing. Whereas no general stimulatory effect could be ascertained at 12 days, higher rhFGF-2 doses decreased bone formation by both intraosseously and periosteally derived cells. At 24 days, a clear, although rather limited, stimulatory effect on osteogenesis was observed, but again a decrease was observed with the 1 microg dose. At both observation periods, an increased number of osteocytes was found in the newly formed bone at sites treated with the lower rhFGF-2 doses, whereas the high-dose rhFGF-2 resulted in a return to control levels, irrespective of whether cells were intraosseously derived or from the periosteum also. Based on differential analysis of bone healing by cells from different sources as well as on bone cellularity, the results suggest that rhFGF-2 in vivo exerts a stimulatory effect on proliferation of committed osteoblastic cells. This effect is biphasic, in that higher doses are without effect or may even be inhibitory. No inductive effect on osteoblast recruitment could be found. These effects differ from those of, for instance, BMP-2 and TGF-beta1.

Bone-inductive efficacy of recombinant human bone morphogenetic protein-2 expressed in Escherichia coli: an experimental study in rat mandibular defects.

Because to our knowledge the efficacy of prokaryotically expressed recombinant human bone morphogenetic proteins (rhBMP) to promote orthotopic osteogenesis has not previously been investigated, our aim was to test the efficacy of rhBMP-2 produced in Escherichia coli to promote bone healing in a standardised experimental bone healing model in rat mandibles. Different doses of rhBMP-2 were delivered in an absorbable collagen sponge carrier, and microporous barrier membranes were placed over half the number of defects in each treatment group, thereby making intraosseous cells the only recruitment source for new osteogenic cells. Results were evaluated by computerised image analysis after 12 and 24 days. The relative efficacy of rhBMP-2 preparations of different purity was also compared. E coli-produced rhBMP-2 stimulated bone healing, but its efficacy was estimated to be about one order of magnitude less than that of rhBMP-2 expressed in eukaryotic cells. We conclude that bacterially expressed rhBMP-2 is osteogenic in vivo, although higher doses will be required than of rhBMP-2 expressed in mammalian cell lines.

[Cerebrocrast correction of reparative osteogenesis on the background of chronic stress]. / Korektsiia tserebrokrastom reparativnogo osteogenezu na foni khronichnogo stresu.

Protective action of cerebrokrast--a derivative from 1,4-dihydropyridine--on the processes of reparative osteogenesis in rats in case of combined action of chronic emotional-pain stress and trauma of mandibular was determined. It is stipulated by a antioxidant properties of cerebrokrast, as well as its stabilizing influence on glycoproteins and calcium homeostasis. The redeived data extend the idea about general-metabolic action of the investigated nootrop at the level of the whole organism and testify worthwhile of its use for prophylaxis of extreme conditions.

Effects of ipriflavone on perialveolar bone formation.

The effect of ipriflavone (IP), a synthetic isoflavonoid derivative, on in vivo bone formation was studied in rat perialveolar bone by surgically producing a hole in the mandibular bone. The holes were filled either with powdered IP or with compounds containing no osteoinductive properties such as biostite and Htr (hard tissue replacement). In control animals, the holes were left to heal spontaneously. The animals were killed 3, 28, and 40 days after surgery and a detailed morphological and morphometric study was performed on the perialveolar bone surrounding the wounds. Three days after surgery (inflammatory phase) the bone wounds were occupied by hemorragic and inflammatory cells in both the untreated and IP-treated bone defects. Twenty-eight days after surgery, bone formation was evident with new bone spiculae particularly concentrated in the area of the bone lesion closest to the adjacent periodontal ligament. Morphometric measurements of the areas occupied by new bone showed that the synthesis of perialveolar bone was significantly stimulated by IP. The repair of the bone defects by new bone formation progressed by day 40, but only in the presence of IP were the original holes almost completely repaired. Conversely, biostite and Htr did not influence promotion of new bone formation. In conclusion, the results of the present study are consistent with a role of IP in stimulating osteogenesis and suggest that this compound could represent a potential therapeutic tool to promote repair of injured perialveolar bone.