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PubMed2002

Bone remodelling and tumour grade modifications induced by interactions between bone and swarm rat chondrosarcoma.

Chondrosarcoma is currently defined as a malignant cartilage tumour arising de novo or within a pre-existing benign cartilage tumour. Chondrosarcoma can be surgically resected, but all grades have significant rates of local recurrence. The purpose of the present study was to develop an animal intraosseous chondrosarcoma model simulating the progression of human chondrosarcoma and elucidating its behaviour and biology. An intraosseous Swarm rat model was designed to assess interactions between bone and chondrosarcoma. A comparison of tumour grading was carried out according to transplantation site. The effects of chondrosarcoma cells (SRC cells) on the mineralisation capacities of osteoblasts and on osteoclast differentiation were studied in relation to modifications observed in vivo at the cellular level. Transplantation of Swarm rat chondrosarcoma within bone marrow or contiguous to induced periosteal lesions led to extensive bone remodelling with trabecular bone rarefaction and periosteal apposition. Transplantation in close contact to bone but without any periosteal lesion had no effect on bone, suggesting that bone healing factors interact with tumour development. With the intramedullary model, the development of tumours of different grade confirms that bone environment is an important factor in malignancy. A decrease of bone nodule formation was noted after cocultures of SRC cells with rat bone marrow, but there was no modification of osteoclast differentiation after cultures of total rabbit bone cells with SRC cells. These data reveal the importance of interactions between bone environment and tumour in inducing bone remodelling and variations in tumour malignancy.

Animals↗
PubMed1995

Chronic intramedullary infusion of prostaglandin E2 stimulates bone formation both in the bone marrow and in the periosteum.

Prostaglandin E2 (PGE2) has a potent bone resorbing activity in vitro, but some recent studies have shown that PGE2 stimulates bone formation in vivo. The effects of PGE2 on the bone are therefore still controversial. We attempted to reveal the effects of PGE2 on bone in vivo more directly; we injected PGE2 continuously into the bone marrow and onto the periosteum and examined the local effects of PGE2 histologically or by bone densitometry. Following PGE2 infusion into the bone marrow, new bone was formed in the bone marrow around the infused site and following PGE2 infusion onto the periosteum, extensive periosteal bone formation was observed. Bone mineral content was also increased significantly in the PGE2 infused bones. The administration of cyclic AMP did not mimic the effects of PGE2. In contrast to in vitro experiments, the in vivo effect of PGE2 is predominantly to produce bone.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2004

Bone turnover markers and bone strength during the first weeks of life in very low birth weight premature infants.

OBJECTIVE: To determine the association between changes in bone turnover markers and bone strength of very low birth weight infants during the first eight postnatal weeks. STUDY DESIGN: Twelve very low birth weight premature infants [mean gestational age: 28.4 +/- 0.6 weeks, mean birth weight: 1131 +/- 62 grams] participated in the study. Bone strength was evaluated weekly by quantitative ultrasound measurements of tibial bone speed of sound (SOS, Sunlight Omnisense). Bone specific alkaline phosphatase (BSAP), a marker of bone formation, and carboxy terminal cross-links telopeptide of type-I collagen (ICTP), a marker of bone resorption, were collected at the ages of one, four and eight weeks. RESULTS: BSAP increased significantly (from 119.9 +/- 16.2 U/L to 132.1 +/- 11.9 U/L and 152.1 +/- 15.7 U/L at one, four and eight weeks of life, respectively, p<0.05). ICTP decreased significantly during the study period (from 122.3 +/- 8.7 ng/ml to 96.0 +/- 4.8 ng/ml and 92.3 +/- 5.4 ng/ml at one, four and eight weeks of life, respectively; p<0.05). There was a significant decrease in bone SOS (from 2886 +/- 29 m/sec to 2792 +/- 30 m/sec and 2753 +/- 30 m/sec at birth, four weeks and eight weeks of life, respectively; p<0.02). There was no correlation between the levels of bone markers and bone SOS. CONCLUSION: In VLBW premature infants, there is a significant decrease in bone strength concomitant with biochemical evidence for new bone formation (increase in BSAP and a decrease in ICTP) during the first eight postnatal weeks. Changes in the biochemical markers could not predict the changes in bone strength.

Aging↗
PubMed2004

Alveolar bone regeneration for immediate implant placement using an injectable bone substitute: an experimental study in dogs.

BACKGROUND: The aim of the present study was to assess the efficacy of a ready-to-use injectable bone substitute for bone regeneration around dental implants placed into fresh extraction sockets. METHODS: Third and fourth mandibular premolars were extracted from three beagle dogs and the interradicular septa were surgically reduced to induce a mesial bone defect. Thereafter, titanium implants were immediately placed. On the left side of the jaw, mesial bone defects were filled with an injectable bone substitute (IBS), obtained by combining a polymer and biphasic calcium phosphate ceramic granules. The right defects were left unfilled as controls. After 3 months of healing, specimens were prepared for histological and histomorphometric evaluations. RESULTS: No post-surgical complications were observed during the healing period. In all experimental conditions, histological observations revealed a lamellar bone formation in contact with the implant. Histomorphometric analysis showed that IBS triggers a significant (P<0.05) increase in terms of the number of threads in contact with bone, bone-to-implant contact, and peri-implant bone density of approximately 8.6%, 11.0%, and 14.7%, respectively. In addition, no significant difference was observed when number of threads, bone-to-implant contact, and bone density in the filled defects were compared to the no-defect sites. CONCLUSION: It is concluded that an injectable bone substitute composed of a polymeric carrier and calcium phosphate significantly increases bone regeneration around immediately placed implants.

Alveolar Process↗
PubMed2000

Age- and sex-related bone uptake of Tc-99m-HDP measured by whole-body bone scanning.

UNLABELLED: AIM of this study was to validate a recently introduced new and easy-to-perform method for quantifying bone uptake of Tc-99m-labelled diphosphonate in a routine clinical setting and to establish a normal data base for bone uptake depending on age and gender. METHODS: In 49 women (14-79 years) and 47 men (6-89 years) with normal bone scans as well as in 49 women (33-81 years) and 37 men (27-88 years) with metastatic bone disease whole-body bone scans were acquired at 3 min and 3-4 hours p.i. to calculate bone uptake after correction for both urinary excretion and soft tissue retention. RESULTS: Bone uptake values of various age-related subgroups showed no significant differences between men and women (p > 0.05). Furthermore, no differences could be proven between age-matched subgroups of normals and patients with less than 10 metastatic bone lesions, while patients with wide-spread bone metastases revealed significantly increased uptake values. In both men and women highest bone uptake was obtained (p < 0.05) in subjects younger than 20 years with active epiphyseal growth plates. In men, bone uptake slowly decreased with age up to 60 years and then showed a tendency towards increasing uptake values. In women, the mean uptake reached a minimum in the decade 20-29 years and then slowly increased with a positive linear correlation of age and uptake in subjects older than 55 years (r = 0.57). CONCLUSION: Since the results proposed in this study are in good agreement with data from literature, the new method used for quantification could be validated in a large number of patients. Furthermore, age- and sex-related normal bone uptake values of Tc-99m-HDP covering a wide range of age could be presented for this method as a basis for further studies on bone uptake.

Adolescent↗
PubMed1997

[An experimental study on the effect of xenogeneic bone combined with human recombinant bone morphogenetic protein-2].

OBJECTIVE: To determine the ability of a new type of composited xenogeneic bone to repair the bone defect. METHODS: The new type of composited xenogeneic bone was obtained by combining the treated cancellous bone with recombinant human bone morphogenetic protein-2 (rhBMP-2) and was implanted in the bone defect of rabbit. RESULTS: There were a large amount of new bone formation within the combined material and the amount was increasing as the time lapsed in the area of the bone defect. In contrast, there were a lot of fibrous tissues with a little new bone formed when the treated cancellous bone was implanted alone. CONCLUSION: The results imply that the rhBMP-2 plays a very important role in new bone formation and the composited xenogeneic bone appears to be an ideal material for the repair of bone defect.

Animals↗
PubMed2002

[How is bone formed and resorbed?-- molecular mechanisms of bone formation and resorption].

Bone has developed as a storage of calcium as well as a supporting tissue in vertebrates. Bone is a complex tissue in which resorption and formation take place throughout life. This process is called bone remodeling. Osteotrophic hormones such as 1 alpha,25-dihydroxyvitamin D3[1 alpha,25 (OH) 2D3], parathyroid hormone (PTH) and calcitonin maintain serum calcium homeostasis within a narrow range of 9 to 10 mg/dl by regulating intestinal absorption of calcium and bone remodeling. Bone tissue contains various types of cells, of which bone-forming osteoblasts and bone-resorbing osteoclasts are mainly responsible for bone remodeling. Osteoblasts arise from common progenitors with chondrocytes, myotubes and adipocytes. Recently, four research groups independently identified core-binding protein alpha-1(Cbfa-1) as a key transcription factor for osteoblast differentiation and bone formation, since Cbaf-1 knockout mice completely lacked bone formation due to maturation arrest of osteoblasts. In contrast, multinucleated osteoclasts are primarily responsible for bone resorption. The recent discovery of new members of tumor necroses factor (TNF) receptor-ligand family has indicated the precise mechanism by which osteoblasts/stromal cells regulate osteoclast formation. Osteoblasts/stromal cells express a new member of the TNF ligand family "osteoclast differentiation factor (ODF)" as a membrane-associated factor. Osteoclast progenitors which express ODF receptor(RANK) recognize ODF through cell-to-cell interaction with osteoblasts/stromal cells, then differentiate into osteoclats. Osteoprotegerin (OPG)/osteoclastogenesis inhibitory factor (OCIF) is a soluble decoy receptor for ODF. Thus, ODF, RANK and OPG/OCIF are the three key molecules for osteoclast formation. The discovery of Cbfa-1 and ODF may establish a new way to treat several metabolic bone diseases caused by abnormal bone formation and resorption.

Bone Resorption↗
PubMed2003

[BMP-2 gene modified tissue-engineered bone repairing segmental tibial bone defects in goats].

OBJECTIVE: To evaluate the effectiveness of the tissue-engineered bone substitute loaded with adenovirus mediated human bone morphogenetic protein-2 gene (Adv-hBMP-2) transfected bone marrow derived mesenchymal stem cells (BMSC) in the repair of diaphyseal segmental bone defect of large animal. METHODS: The right tibial bone defects (2.6 cm) model of 26 goats were established and divided into 5 groups: I. Adv-hBMP-2 transfected BMSC/calcined bone (CB) group (n = 9); II. adenovirus-beta-galactosidase (Adv-betagal) gene transfected BMSC/CB group (n = 6); III. untransfected BMSC/CB group (n = 6); IV. single CB group (n = 3); VI. untreated group (n = 2). The above tissue-engineered bone substitutes were implanted in the bone defects respectively except group VI. Roentgenography, histomorphometrical analysis and biomechanical measurement were studied at various times. RESULTS: X-ray: at 4 - 8th weeks after implantation, more bony callus was found in the bone defects of group I. The complete healing rates of group I, II, III, IV, and V were 5/8, 1/5, 0/5, 0/2, 0/1 respectively at 26th week after implantation. Histomorphometrical analysis showed much more new bony callus including cortical bone formed in group I than those of other groups. The compression strength of the implanted bone substitute of group I is significantly higher than those of group II and III. CONCLUSION: The tissue-engineered bone substitute loaded with human BMP-2 gene transfected BMSC can repair diaphyseal segmental bone defect of large animal (goat).

Animals↗
PubMed2005

[Biological activities of bone morphological protein in bone regeneration].

Bone matrix contents various development factors which control structuring and absorption and those factors play important role in bone and cartilage development. Bone morphological proteins are members of TGF-beta super family and their activity is certain becoming from the bone. This activity leads to the serial development processes which include chemo taxis, proliferation and differentiation which results in trans resistant formation of cartilage as well as production of life cells of a bone tissue. Biological activities of re combinative human bone morphogenetic protein 7 (rhBMP-7). induction bone formation of non critical size mandible defect of New Zealand rabbits were researched in the study. Markers of osteoblastic differential in the study included ALP specific activity. Histological analysis performed 7, 14, 30, 60 postoperative days, C-T analysis with determination Bone Mineral Density value of new structured tissue within the defect was done 30 days. Results indicate that ectopic bone formation has been inducted with rhBMP-7 and histological analysis shown mature bone with collagen and ostheociti 60th day. Early 7 day granulocyte tissue with angiogenesis was detected, and after 30 days ostheoblastsis shown with a lot of vascular and mezenhimal tissue. Ostheogenetic processes were characteristic for typical inter membraneous ossification without cartilage tissue. ALP activity was significantly increased 21 days. C-T and Bone Mineral Density value shown density of new structured tissue determinate as bone (413 mg/cm3 and 519 mg/cm3). Studies showed that concentration of 100 mg rhBMP-7 in collagen as career had strong ostheo inductive capacity. Conditions which module BMP depend ostheo induction should be considered in the future. Information could lead to improvements of rhBMP as substitution for bone graft in clinical practice.

Animals↗
PubMed2006

[Quantitative and qualitative comparison of the maxillary bone regeneration after beta-tricalcium phosphate and autogenous bone implantation].

Graft insertion can effectively enhance the regeneration of debilitated bone. The effects of an alloplastic bone-replacing material, beta-tricalcium phosphate (Cerasorb), and of autogenous bone graft were compared. In 17 edentulous patients, the maxillary sinus floor was extremely atrophied to such an extent that implant placement was impossible. The Schneiderian membrane was surgically elevated bilaterally by insertion of Cerasorb (experimental side) and autogenous bone graft (control side). After surgery, the recovery was followed clinically and radiologically. After 6 months, 68 bone cylinders were excised from the grafted areas and implants were inserted into their places. The bone samples were embedded into resin, and the osteointegration of the grafts was studied histologically. Trabecular bone volume (TBV) and trabecular bone pattern factor (TBPf) were quantified by histomorphometry. Cerasorb proved to be an effective bone-replacing material with osteoconductivity; it was capable of gradual disintegration, thereby providing space for the regenerating bone. The new bone density was not significantly different on the experimental and control sides (32.4 +/- 10.9% and 34.7 +/- 11.9%, respectively). However, the graft biodegradation was significantly slower on the experimental side than on the control side. The TBPf value was lower on the control side than on the experimental side (-0.53 +/- 1.7 mm(-1) and -0.11 +/- 1.4 mm(-1), respectively); but this difference was not significant. Six months after insertion of the grafts, the bone of the augmented sinus floor was strong and suitable for anchorage of dental implants, irrespective of whether autogenous bone or Cerasorb particles had been applied.

Adult↗
PubMed1991

[Vertebral bone density and its correlation with various factors related to bone metabolism in alcoholics: a quantitative study by computed tomography].

We measured vertebral bone density of 59 male alcoholics (ALC) using quantitative computed tomography (QCT). Bone density of ALC was decreased measured on admission compared with age-matched healthy male controls (ALC: 144 +/- 42, CONTROLS: 173 +/- 34 mg/cm3, p less than 0.05). The bone density was not correlated with serum ALP, Ca, and Pi. Serum parathyroid hormone and calcitonin were also not correlated with the bone density in ALC. Serum 25-(OH)-D showed significant positive correlation with the bone density (p less than 0.01) and 1,25-(OH)2-D showed trend of positive correlation with the bone density (p less than 0.01) in ALC. Severity of liver diseases did not have any relation to the bone density in ALC. Although the decreased bone density was not improved at the second QCT examined about 10 weeks after first QCT without medication, patients administered 1 microgram of 1 alpha-(OH)-D3 daily showed a significant increase in the bone density (on admission: 152 +/- 37, 10 weeks later: 162 +/- 35 mg/cm3, p less than 0.02). Combination therapy of 1 alpha-(OH)-D3 and calcitonin did not increase the bone density. These results indicate that bone density was decreased in ALC and a decrease in serum vitamin D metabolites may cause a decrease in the bone density, although liver dysfunction does not have a role in it. These data also suggest that 1 alpha-(OH)-D3 is effective in an increase in the bone density in ALC with osteoporosis after abstinence.

Adult↗
PubMed1982

Skeletal remodelling and bone related hormones in two adults with increased bone mass.

This study of two cases documents increased bone mass in a 30-yr old man and osteopetrosis in a 38-yr-old woman and examines the patients in terms of radiologic features, bone photon absorptiometry and bone biopsy analyses which include tetracycline kinetics. Both patients had elevated bone mass based on quantitative bone histology of iliac crest biopsies normal, or low PTH, and normal calcitonin values. However, they differed markedly from each other in other respects: One patient possessed significantly increased rates of bone formation and mineralization, had elevated serum alkaline phosphatase, increased total hydroxyproline over a 24 hour urine collection but displayed a normal amount of bone surface involved in resorption. The other subject had normal bone formation parameters, but had elevated serum acid phosphatase and a significantly elevated resorbing (crenated) surface. Although most theories ascribe and cause of osteopetrosis to decreased resorption, our study shows that increased bone formation, even when accompanied by normal resorption, can lead to the abnormal accumulation of bone mass. In this respect, the resorptive response of this patient was abnormal; the normal coupled relationship between bone formation and bone resorption, which ensures proper control of endosteal bone volume, had been lost.

Acid Phosphatase↗
PubMed1993

[Reconstruction for malignant bone tumor defects by a composite graft--plasty of the bone defect not involving a joint].

Malignant bone tumors excluding joints of six patients were resected. The resultant bone defects were reconstructed with a synthetic fabric-enveloped hydroxyapatite spacer in five cases and a filler in one. Dacron fabric was used in four cases and each of Marlex mesh and Dexon mesh were used in one. The grafting and reconstruction processes were studied clinically and roentgenographically. CT scan was used in one case. The synthetic fabrics were helpful in repairing released supporting soft tissue by serving as a scaffold for the formation of new connective tissue. The spacer to the supporting soft tissues was biologically fixed. The synthetic fabrics were capable of inducing and supporting of the ingrowth of vascular connective tissue. The anchor of reconstructed supporting soft tissue became increasingly strong as time passed. For lasting and stable reconstruction, the spacer must be made uniform with the remaining bone by making an extracortical bone bridge using an autogenous bone graft. In two cases, autogenous bone grafts were taken from the ilium to bridge the remaining bone. The autogenous bone grafts were fixed to the spacer by enveloping the bone graft and the spacer with Marlex mesh and Dexon mesh. In the Marlex case roentgenographic findings showed that extracortical bone bridging was completed within six months after the operation. In the Dexon mesh case, extracortical bone bridging was not completed at one year after the operation, however the repair of the released supporting soft tissues was satisfactory. In order to avoid complications, a fabric must be absorbed fully after completion of the biologic fixation and extracortical bone bridging. Yet, further investigations are required to determine which of the synthetic fabrics and mesh sizes to enhance incorporation of the bone graft.

Adult↗
PubMed1996

Clinical efficacy of bone alkaline phosphatase and prostate specific antigen in the diagnosis of bone metastasis in prostate cancer.

PURPOSE: We investigated the usefulness of bone alkaline phosphatase isoenzyme and prostate specific antigen (PSA) determined by radioimmunoassay to predict bone scan evidence of metastasis in newly diagnosed untreated and treated prostate cancer. MATERIALS AND METHODS: We analyzed bone alkaline enzyme concentrations in 350 men, including 150 controls, 100 with benign prostatic hyperplasia and 100 with prostate cancer (52 with stages T1 to 4, M0 and 48 with stages T1 to 4, M1 to 4). We also analyzed bone alkaline phosphatase enzyme concentrations in 61 stages T1 to 4, M0 prostate cancer cases during followup after radical prostatectomy or hormonal therapy, and 17 had clinical progression (9 with local, 5 with lymph node and 3 with bone metastases). Simultaneously, we analyzed PSA concentrations. RESULTS: Average bone alkaline phosphatase enzyme levels were 12, 11.1 and 10.0 ng./ml. in the control, benign prostatic hyperplasia and stage M0 prostate cancer groups, respectively (p not significant), and 83.2 ng./ml. in patients with stage M1 to 4 disease (p<0.001). Considering that to diagnose bone metastasis the cutoff for bone alkaline phosphatase enzyme and PSA is 30 ng./ml. and 100 ng./ml., respectively, clinical effectiveness was 93.7% and 81.8%, respectively. Finally, measurement of both substances at the same time increased clinical effectiveness to 97.9%. During followup a bone alkaline phosphatase enzyme level that becomes greater than 30 ng./ml. (0% in the local and lymphatic progression groups, and 100% in the bone metastasis group) indicates the need to perform a bone scan. CONCLUSIONS: We recommend the clinical use of bone alkaline phosphatase enzyme determined by radioimmunoassay and PSA measurement for the diagnosis of bone metastases and progression of prostate cancer because of the good sensitivity and specificity.

Aged↗
PubMed1996

[Cross sectional study of the relationship between bone density to diet and life style using ultrasound bone densitometry].

The relationship between bone density to diet and life style was investigated in pre- and postmenopausal women in Kyoto Prefecture in 1994 by a cross-sectional study. Bone densities of 453 women aged 30-86 years were measured by ultrasound bone densitometry. History of pregnancy and delivery, menstruation, medical history, bone and arthral symptoms, life style, food intake frequency, current and past intake of dairy products, and physical activity were examined by self-administered questionnaire. Analysis of covariance and multiple-regression analysis were performed to determine the relation between bone density and life style adjusted for age and obesity index among 151 premenopausal women (PRE), 244 postmenopausal but not sedentary (under 65 years of age) women (POST), and 58 sedentary (older than 65 years of age) women (SED). The results were as follows; 1) A marked age-related decline in bone density was observed at 45-55 years of age. The correlation coefficient between age and bone density was significant at -0.65 (p < 0.01). 2) Obesity index and bone density were positively correlated in each group. 3) Among the PRE group women, there was no relation between life style and bone density. Those who experienced bone fractures tended toward low bone density. Among the POST group, time since menopause, exercise, and current milk intake were significantly correlated with bone density. In the SED group, women with arthralgia showed significantly lower densities. 4) From multiple-regression analysis, age, obesity index, and milk intake during childhood were shown to be related to bone density in each group.

Adult↗
PubMed2005

Repairing of goat tibial bone defects with BMP-2 gene-modified tissue-engineered bone.

Bone defects larger than a critical size are major challenges in orthopedic medicine. We combined tissue-engineered bone and gene therapy to provide osteoprogenitor cells, osteoinductive factors, and osteo-conductive carrier for ideal bone regeneration in critical-sized bone defects. Goat diaphyseal bone defects were repaired with tissue and genetically engineered bone implants, composed of biphasic calcined bone (BCB) and autologous bone marrow derived mesenchymal stem cells (BMSC) transduced with human bone morphogenetic protein-2 (hBMP-2). Twenty six goats with tibial bone defects were divided into groups receiving implants by using a combination of BCB and BMSCs with or without the hBMP-2 gene. In eight goats that were treated with BCB that contained hBMP-2 transduced BMSC, five had complete healing and three showed partial healing. Goats in other experimental groups had only slight or no healing. Furthermore, the area and biochemical strength of the callus in the bone defects were significantly better in animals treated with genetically engineered implants. We concluded that the combination of genetic and tissue engineering provides an innovative way for treating critical-sized bone defects.

Animals↗
PubMed1997

In vitro and in vivo effects of ipriflavone on bone formation and bone biomechanics.

Ipriflavone (i.p.) positively affects bone density in postmenopausal osteoporosis, primarily by inhibiting bone resorption. Using in vitro models of human osteoblast differentiation, we have observed that i.p. and some of its metabolites stimulate the expression of bone sialoprotein, decorin, and type I collagen, and facilitate the deposition of mineralized matrix. This suggests that i.p. may stimulate bone formation in addition to its antiresorptive activity. To assess whether these effects translate into an improved bone "quality" in vivo, we measured biomechanical properties, mineral composition, and crystallinity of femurs of 12-week-old, male, Sprague-Dawley rats treated with i.p. for 1 month. i.p. significantly decreased vibration damping, an index of strain energy loss. Because vibration damping increases as bone porosity increases, the results indicate that i.p.-treated bones acquired a higher capacity to withstand dynamic stress. In fact, 1.5-fold higher energy was required to fracture femurs of i.p.-treated rats after a single supramaximal impact. i.p. also increased BMD, assessed by both volume displacement and ash analysis, whereas the relative contents of Ca, P, and Mg in the ashes were not affected. Thus, no gross abnormalities in mineral composition of bone occurred after i.p. administration. As a measure of bone crystallinity, X-ray diffraction analysis was performed. The broadening parameter beta 1/2 for the (310) and (002) reflections was not significantly different between i.p.-treated and control animals. Similarly, there were no differences in serum levels of Ca, Mg, alkaline phosphatase, and type I collagen telopeptides between treated and control animals at the end of the study. Therefore, 1-month treatment with i.p. increased bone density and improved the biomechanical properties of adult male rat bones without altering mineral composition or bone crystallinity.

Animals↗
PubMed1996

Evolution of bone transplantation: molecular, cellular and tissue strategies to engineer human bone.

Bone defects occur in a wide variety of clinical situations, and their reconstruction to provide mechanical integrity to the skeleton is a necessary step in the patient's rehabilitation. The current gold standard for bone reconstruction, the autogenous bone graft, works well in many circumstances. However, autograft reconstruction, along with the available alternatives of allogenous bone graft or poly(methylmethacrylate) bone cement, do not solve all instances of bone deficiency. Novel materials, cellular transplantation and bioactive molecule delivery are being explored alone and in various combinations to address the problem of bone deficiency. The goal of these strategies is to exploit the body's natural ability to repair injured bone with new bone tissue, and to then remodel that new bone in response to the local stresses it experiences. In general, the strategies discussed in this paper attempt to provide the reconstructed region with appropriate initial mechanical properties, encourage new bone to form in the region, and then gradually degrade to allow the new bone to remodel and assume the mechanical support function. Several of the concepts presented below are already finding clinical applications in early patient trials.

Biocompatible Materials↗