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Biomedical subjects

M R Urist

Publications and source records attributed to M R Urist.

At least 37 records · Page 2Linked to original sources
PubMed1996

Bone morphogenetic protein-induced heterotopic bone in osteopetrosis.

The objectives of the present research on the osteopetrotic mouse are to investigate the factors influencing heterotopic bone development. The osteopetrotic mutant was deficient in macrophage colony stimulating factor and failed to activate functioning monocytes, macrophages, and osteoclasts. Macrophage colony stimulating factor deficiency also caused a heretofore undescribed delay in organization and absorption of hematomas resulting from surgical operations. Surgically implanted in a heterotopic site, bone morphogenetic protein induced approximately 10% more bone in osteopetrotic than littermate+/? mice. Radiographically, the heterotopic bone was at least 50% denser than new bone. The new bone was metachromatic or slightly basophilic rather than eosinophilic and undermined with large deposits of hypercalcified hypertrophic cartilage. Bone mineral in the osteopetrotic mouse was deposited in an apatite-like form with a higher calcium/phosphorus ratio than the bone of +/? littermates. High levels of alkaline phosphatase synthesis were sustained longer in the osteopetrotic mouse than in the +/? littermate. Tartrate resistant acid phosphatase synthesis was almost nil in osteopetrotic mice during the first 4 weeks, and thereafter appeared coincidental with spontaneous remission of osteopetrosis at 6 weeks. Implants of the mineralized cortical bone matrix of the osteopetrotic mouse showed minimal if any bone morphogenetic protein activity of matrix of +/? littermate or otherwise normal mice. The cause of the remission of the bone disorder in the osteopetrotic mouse is not known but is of great interest to students studying the problem of coupling of bone formation to bone resorption.

Animals↗
PubMed1996

Recombinant human bone morphogenetic protein (rhBMP) induced heterotopic bone development in vivo and in vitro.

In vivo, recombinant human bone morphogenetic protein (rhBMP-2) with deactivated bone matrix as a carrier, implanted in muscle in adult rates, induced development of heterotopic bone, including bone marrow. The volume of bone was proportional to the dose of rhBMP-2 in a range of 0.2-150 microg. In vitro, in response to 50-microgram dose range, subcutis- and brain-derived outgrowths differentiated into loosely woven connective tissues composed of spindle-shaped fibroblasts, adipocytes, and cartilage. Muscle-derived connective tissues cultivated first in culture media supplemented with 50 microgram of rhBMP-2 for 72 hr, then enclosed in a diffusion chamber, and immediately transplanted into a rectus abdominous muscle pouch in an autogenic rat for 28 days, induced cartilage development on the inside and transmembrane hetertoptic bone development including bone marrow on the outside. These experiments are interpreted to show that muscle derived connective tissue cells have the competence of embryonic cells to develop de novo in response to BMP in postfetal life.

Animals↗
PubMed1996

Bone morphogenetic protein-2: biology and applications.

Bone morphogenetic protein-2 is a low molecular weight glycoprotein, classified as a morphogen. The sine qua non of bone morphogenetic protein is consistently reproducible induction of bone development in heterotopic sites. Bone morphogenetic proteins belong to the expanding transforming growth factor-beta superfamily. Bone morphogenetic protein-2 has pleiotropic functions that range from extraskeletal and skeletal organogenesis to bone generation and regeneration. Bone morphogenetic protein induced bone formation in postfetal life recapitulates the process of embryonic and endochondral ossification. Through recombinant gene technology, human bone morphogenetic protein-2 is available in almost unlimited amounts for basic research and clinical trials. Human bone morphogenetic protein-2 induces structurally sound orthotopic bone in a variety of experimental systems, including femoral defects in rats, tibial and ulnar defects in rabbits, femoral defects in sheep, mandibular defects in dogs, spinal fusion in dogs, and porous ingrowth in rats. Human bone morphogenetic protein-2 research extends to the fields of developmental biology, genetics, and evolution. Bone morphogenetic protein has been used successfully at the authors' institution to heal clinical nonunions and to achieve spinal fusion. This report reviews the current understanding of bone morphogenetic proteins in general and BMP-2 in particular and summarizes their potential applications.

Animals↗
PubMed1996

Demineralized bone matrix supplied by bone banks for a carrier of recombinant human bone morphogenetic protein (rhBMP-2): a substitute for autogeneic bone grafts.

Four commercially available preparations of demineralized freeze-dried human bone powders (DFDB) were investigated for endogenous bone morphogenetic protein (BMP) as observed by osteoinductive activity. Composites of DFDB without and with 1 microgram or 10 micrograms of recombinant human bone morphogenetic protein-2 (rhBMP-2) were implanted into the hindquarter muscles of Swiss-Webster mice. The four batches of DFDB without rhBMP-2 were placed also in hindquarter muscles of athymic mice. Three weeks after implantation, the area of induced bone and cartilage formation was measured by radiographic and histomorphometric methods. In normal mice, without rhBMP-2, DFDB implants induced development of dense fibrous connective tissue with minimal, if any, new bone. In athymic mice, DFDB induced development of small patches of appositional new bone. In contrast, in normal mice, composites of DFDB and rhBMP-2 induced development of large areas of heterotopic bone and bone marrow formation. The bone morphogenetic response occurred with a statistically significant difference (p < 0.0001) between implants of 1 microgram and the 10-microgram rhBMP-2 composites. Thus, DFDB from all four bone banks demonstrated comparable capacity to serve as a carrier for rhBMP-2.

Analysis of Variance↗
PubMed1995

Human demineralized freeze-dried bone: inadequate induced bone formation in athymic mice. A preliminary report.

The purpose of this study was to test the osteoinductive properties of demineralized freeze-dried bone (DFDBA) randomly purchased from four commercial bone banks. Twenty-five (25) milligrams of bone from each of the banks was implanted into the hindquarter muscles of athymic mice. Two samples from each of the banks were compared with samples from the other banks. A total of 16 implants were grafted into 8 mice. Two additional mice served as controls. One mouse received an implantation of deactived human cortical bone matrix (DBM) (negative control). The other mouse received an implant of human bone morphogenetic protein/non-collagenous proteins (hBMP/NCP) infused to surface demineralized human cortical bone (positive control). At 21 days the mice were killed, the hindquarters were photographed, and the tissues were prepared for histologic evaluation. Of the 16 commercial DFDBA implants, 12 were available for histologic evaluation. There was no radiographic evidence of bone formation for the DFDBA implanted mice or the DBM implants. Small bone ossicles were scarcely visible in the hindquarters of the mouse which received the hBMP/NCP infused bone. Histomorphometric analysis was used to determine the percentage of new and dead bone. The bone was measured in pixels. The predominant histologic feature of the DFDBA implants was non-vital bone chips with minimal amounts of new bone. The average amount of non-vital bone ranged from 78.4% to 92.5%. There was no evidence of bone formation for the DBM implants. The average amount of bone for the mouse which received hBMP/NCP was 96%. The results of this pilot study indicate that commercially-available DFDBA induced clinically insignificant amounts of bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Endogenous lipids in matrix-induced bone morphogenesis.

Demineralized matrix was delipidized with chloroform methanol before and after demineralization and implanted in muscle of allogeneic rats. Because lipids are difficult to separate completely from bone collagen, another preparation was gelatinized and delipidized with either chloroform methanol or acetone or both. Bone matrix demineralized without delipidization induced formation of a spherical-shaped deposit of new bone, which was remodeled to form a shell of cortical bone and central pool of normal hematopoietic bone marrow. When the bone was delipidized, only 20% to 25% was resorbed and replaced by new bone; unresorbed matrix failed to recalcify. Gelatinized bone matrix delipidized before implantation was even less well resorbed or replaced by new bone, but 12% to 44% of the matrix residue recalcified. The new deposits of bone were colonized by blood-borne bone marrow-derived stem cells and developed central pools of normal hematopoietic bone marrow. Recalcified residual matrix did not develop bone marrow. Additional investigations are required to determine whether the host bed adipocytes provide the phospholipids for recalcification of bone matrix. There was no preliminary recalcification in matrix-induced bone development, even though the 2 processes may occur simultaneously under specified experimental and pathologic conditions. Additional investigations are in progress to determine whether certain acetone soluble lipids may form the endogenous delivery system for bone morphogenetic protein and induced bone development.

Adipocytes↗
PubMed1994

Bovine bone morphogenetic protein (bBMP/NCP)-induced repair of skull trephine defects in pigs.

Bovine bone morphogenetic protein and associated noncollagenous proteins (bBMP/NCP) were implanted in skull trephine defects, 14 and 22 mm in diameter, in adult minipigs. The defects were larger than the critical size for repair of cranial bones in pigs observed for a period of six to 16 weeks. The trephines were placed either in the nasal bone at eye level, or in the frontal bone. In minipigs the repair was more advanced in trephines in the frontal bone than in the nasal region, but was incomplete in either bone bed. As in dogs, implants of bBMP/NCP in heterotopic sites were resorbed before a competent cell population could respond. Serum anti-BMP antibody was elevated. The IgG levels of the antibody titer showed a clearcut dose-response; the level was significantly higher in one pig with implants of 85 mg of bBMP/NCP proteins in a frontal bone trephine.

Animals↗
PubMed1993

Bone morphogenetic protein inhibits differentiation and affects expression of helix-loop-helix regulatory molecules in myoblastic cells.

Bone morphogenetic protein (BMP) reproducibly induces chondrogenesis and osteogenesis when implanted into skeletal muscle. The exact identity of the cell that responds to BMP is not known. Furthermore, controversy exists regarding the possibility that myoblastic cells may transdifferentiate to chondrocytes and osteoblasts under the influence of BMP. We have therefore, undertaken studies on the effects of BMP on differentiation in L6 and C2C12 cells, two rodent myoblastic cell lines. To gain insights into the mechanisms of action of BMP, we have studied the effects of BMP on the levels of expression of the four known myogenic determination genes: myogenin, Myo D, herculin, and myf-5. BMP inhibited myogenesis in myoblastic cells. Convincing evidence of transdifferentiation of myoblasts to chondrocytes or osteoblasts was not seen. BMP inhibited the expression of all four myogenic determination genes.

Alkaline Phosphatase↗
PubMed1993

Surface adhesion and attachment factors in bone morphogenetic protein-induced chondrogenesis in vitro.

Bone morphogenetic protein (BMP) induces cartilage and bone development in embryonic and post-fetal life. Bone morphogenetic protein-induced chondrogenesis in outgrowths of muscle connective tissues on various furrowed and unfurrowed fibronectin-coated substrata was observed by biochemical and histologic methods. The substrata consisted of cellulose acetate membranes, atelocollagen, denatured autoclaved demineralized bone matrix, bone matrix deactivated by extraction of BMP with guanidine hydrochloride (GuHCl), and aggregates of insoluble BMP and associated noncollagenous proteins (BMP/NCP) prepared from bovine bone. The furrows, which were mechanically cut into the substrata, were intended to increase surface area and provide extra spaces for cell proliferation under compression. The extent to which extracellular attachments were required for induced cartilage development was reflected in the quantity of cartilage formed when BMP/NCP, either in insoluble or in water-soluble form, was introduced was greatest on GuHCl-extracted bone matrix. On cellulose acetate and atelocollagen, BMP-induced cartilage development was relatively scanty. A substratum of bone matrix, denatured by autoclaving at a minimum of 125 degrees, permitted cell-to-cell adhesion but not cell-to-substratum attachments; the end product was loose fibrous connective tissue only. In contrast, cartilage development occurred on surfaces of undissolved particles of BMP/NCP. Water-soluble human BMP induced development of masses of amorphous cartilage. Even after it was extracted with GuHCl, rat bone matrix may have retained trace amounts of endogenous BMP. Thus, when the requirements of cells for cell-to-cell adhesion and cell-to-substratum attachment, including mechanical factors such as furrows to enlarge surface area, were met, cartilage development was a manifestation of temporal, spatial, and BMP distribution patterns. In situ hybridization and immunofluorescent microscopy with the aid of antirecombinant BMP antibiotics may provide new information about morphogenesis.

Animals↗
PubMed1993

Transplant of bone marrow and muscle-derived connective tissue cultures in diffusion chambers for bioassay of bone morphogenetic protein.

To promote a high concentration gradient, syngeneic bone marrow and muscle connective tissue cell cultures and subcultures were exposed to bone morphogenetic protein and associated noncollagenous bone matrix proteins (BMP/NCP) in vitro, transferred to diffusion chambers, and then transplanted into the anterior abdominal wall of isogeneic rats. Both muscle- and marrow-derived cells differentiated into cartilage and chondroosteoid on the inside of diffusion chambers. New bone developed on the vascularized outside surfaces in juxtaposition to avascular tissue on the inside. Levels of glycosaminoglycans (GAGs) and DNA synthesis in tissues inside the chambers were sharply elevated. These data, correlated with histologic observations, demonstrate that the BMP/NCP recruits mesenchymal-type cells for a skeletal tissue pathway of development. Muscle-derived cells, as distinguished from marrow-derived cells, originate in a nonosseous environment but differentiate into osteoprogenitor (osteogenic stem) cells and display levels of DNA synthesis almost as high as marrow stroma-derived cells. The rise in DNA synthesis was maximal in the interval from two to three weeks after transplantation. Whether the bone marrow stroma mesenchymal cell target for BMP is only the osteogenic stem cell population or also includes colony-forming units fibroblasts (CFU-F) remains to be investigated by experiments on established cell lines.

Animals↗
PubMed1993

Osteoinductive activity of composites of bone morphogenetic protein and pure titanium.

Titanium sponges were infused with bone morphogenetic protein (BMP-Ti), and the osteoinductivity of the resultant composite was measured. New bone formation occurred three weeks after implantation and was identified by soft x-ray analysis. Quantitative analysis showed no significant difference between BMP-Ti composites and control samples (BMP only). Consequently, pure titanium neither inhibited nor promoted BMP activity. Chondrocytes and new bone formation occurred in direct contact with the surfaces of the titanium. X-ray microanalysis demonstrated new bone formation inside the pores of the titanium sponges. The BMP-Ti composite has interesting properties as an osteoinductive implant and has potential practical clinical applications.

Animals↗
PubMed1993

Cell differentiation in response to partially purified osteosarcoma-derived bone morphogenetic protein in vivo and in vitro.

Bone morphogenetic protein (BMP) and associated noncollagenous proteins (NCP) were isolated from human osteosarcoma tissue. Implantation of 5- and 10-mg samples induced heterotopic ossification in the mouse quadriceps. Osteosarcoma-derived BMP/NCP induced the same process of osteogenesis as human BMP/NCP isolated from bone matrix in vivo. In vitro continuous perfusion of neonatal rat muscle tissue with 5 micrograms/ml osteosarcoma-derived BMP/NCP increased glycosaminoglycan (GAG) synthesis significantly whereas DNA synthesis was relatively unchanged. Similar results were found when muscle tissue was preincubated with 200 micrograms of osteosarcoma-derived BMP/NCP for four hours followed by an incubation period of 14 days in BMP-free medium: GAG synthesis increased significantly, whereas DNA synthesis did not change. The increase in GAG synthesis coincided with cell differentiation but not cell proliferation. Histologic findings confirmed chondrogenesis in vitro. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that osteosarcoma-derived BMP/NCP included a prominent component with a molecular weight of 18,000 d.

Animals↗
PubMed1992

Resistant nonunions and partial or complete segmental defects of long bones. Treatment with implants of a composite of human bone morphogenetic protein (BMP) and autolyzed, antigen-extracted, allogeneic (AAA) bone.

Twenty-five patients with resistant nonunions including partial or complete segmental defects were treated with a composite alloimplant of human bone morphogenetic protein (h-BMP) and autolyzed, antigen-free, allogeneic bone (AAA). The series consisted of 16 females and nine males; average age was 45 years. Preoperative symptoms averaged 30 months (range, five to 83 months); 22 of 25 patients had failed multiple attempts at electrical stimulation. Twenty-three of 25 patients had an average of three prior failed surgical attempts at union (range, one to ten). There were ten segmental defects with an average length of 4 cm (range, 2-9 cm). The composite implant was incorporated as an onlay in 15 extremities and as an inlay graft supported by internal fixation in ten extremities. Seven patients received supplementary autogeneic cancellous bone grafting. Average healing time was six months (range, three to 14 months). Average follow-up time was 21 months (range, five to 82 months). Functional results were rated as excellent, 14; good, five; and fair, five. One failed to unite because of a recurrent infection. Union was obtained in 24 of 25 patients. There were five failures of the original operation that required reoperations; union eventually occurred in four of five extremities by repeat composite grafting and replacement of the failed internal fixation. Bony union between host bone and the composite implant began at an average of eight weeks postoperatively. Present results indicate that h-BMP/AAA composite implants represent adjunctive treatment of difficult nonunions. The h-BMP/AAA composite implants may be implanted in either partial or complete segmental defects of long bones.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Immune inhibition of repair of canine skull trephine defects implanted with partially purified bovine morphogenetic protein.

The healing of 14-mm trephine skull defects was observed in ten adult mongrel dogs. First and second set trephine operations were performed to determine whether xenogeneic bovine bone morphogenetic protein (bBMP) and associated bone matrix water-insoluble noncollagenous proteins (iNCP) incite an immunological humoral response inhibiting bone repair. The effects of immunization to BMP/iNCP were observed by serum radioimmunoassay, and by correlated roentgenographic and histological analysis of deposits of new bone. The first set implants of bBMP/iNCP induced 96% healing while the regeneration of the second set trephines was 34% less than the first set. The second set was associated with a significant increase in serum anti-BMP antibodies. While xenogeneic bBMP induced complete healing of trephine defects when implanted without previous immunization, and repair in response to a second set of bBMP/iNCP was always incomplete, further research with high purified recombinant BMP is required to measure immune effects in a statistically significant number of pure bred recipients.

Animals↗
PubMed1991

Allogenic bone and cartilage morphogenesis. Rat BMP in vivo and in vitro.

An allogenic aggregate of bone morphogenetic protein (BMP) and insoluble non-collagenous proteins (NCP) as well as a crude GuHCl extract were isolated from rats diaphyseal bones. Intramuscular implantation of 5 mg and 10 mg rat BMP/NCP in rats formed new ossicles, whereas 20 mg GuHCl extract failed to induce heterotopic bone formation. When 6 samples of inactivated rat bone matrix gelatin (BMG) were reconstituted with 0.75 mg of either BMP/NCP or GuHCl extract all 3 matrices reconstituted with BMP/NCP but only 1 out of 3 samples reconstituted with GuHCl extract induced heterotopic bone formation. Inactivated BMG alone did not show any osteoinductive activity. The small amount of BMP/NCP necessary for osteoinduction when recombined with inactivated BMG suggests that growth factors in bone matrix without inherent bone-forming activity enhance BMP activity. In vitro, connective tissue outgrowths of neonatal rat muscle on a substratum of inactivated rat BMG differentiated into cartilage in response to 0.05 microgram/ml, 0.5 microgram/ml and 5.0 micrograms/ml allogenic BMP/NCP added to the medium during the incubation period of 2 weeks. On day 14 of cultivation S35-sulphate incorporation into glycosaminoglycans (GAG) and H3-thymidine incorporation into DNA were measured, and the results related to the DNA content and the weight of the incubated muscle tissue, respectively. All doses of BMP/NCP increased GAG synthesis statistically significantly (p less than 0.05 to p less than 0.001). In contrast to that, DNA synthesis rate was not influenced by BMP/NCP. This suggests that GAG synthesis was not caused by cell proliferation but by cell differentiation.

Abdominal Muscles↗
PubMed1991

Induced bone development in transplants of fresh human pseudomalignant heterotopic ossification tissue in athymic nude mice.

Biopsy specimens of mature trabecular bone from tumors of two typical cases of pseudomalignant heterotopic ossification (PHO; myositis ossificans circumscripta) were transplanted into athymic nude mice. Specimens of normal metaphyseal bone in adjacent areas were also transplanted in the contralateral hindquarter muscles for controls. By seven days, control bone transplants were necrotic and enveloped in granulation tissues whereas PHO transplants were surrounded by proliferating connective tissue derived from the host-bed muscle tissues. In the intervals from 14 and 21 days, the PHO transplants showed vascular and hypertrophied connective-tissue proliferation with appositional deposits of new bone. The microscopic features of the new bone suggested that it was of mouse host-bed origin because the new bone from Case 1, a female, showed nuclei without sex chromatin. The quantities of new bone were measured by correlated histomorphometric and computer image analysis of microradiographs. Little or no cartilage development was noted at any stage. The normal control trabecular bone tissue was slowly resorbed by macrophages and mononuclear phagocytes; multinucleated giant cells were few and relatively small. Except in one questionably small area of one transplant, nontumorous undemineralized normal human bone failed to induce bone formation within the 28-day period of observation. The quantity of new bone formed in athymic mice in response to implants of PHO, estimated from equivalent quantities of bone developed from implants of lyophilized matrix-free bone morphogenetic protein (BMP) was about 1 microgram/g of wet PHO tumor weight. Although circumstantial evidence implicates BMP in the pathogenesis of heterotopic ossification, more research should be directed toward regional and systemic factors inhibiting bone development in normal and abnormal conditions, including malignant bone tumors.

Adult↗
PubMed1990

Bone morphogenetic protein-mediated interaction of periosteum and diaphysis. Citric acid and other factors influencing the generation of parosteal bone.

In rabbits, after long-bone growth is complete and the cambium layer regresses, mesenchymal-type cells with embryonic potential (competence) for bone development persist in the adventitial layer of periosteum. These cells are not determined osteoprogenitor cells (stem cells) because bone tissue differentiation does not occur when adult periosteum is transplanted into a heterotopic site. In this respect, adventitial cells differ from bone marrow stroma cells. In a parosteal orthotopic site in the space between the adult periosteum and diaphysis, implants of bone morphogenetic protein (BMP) and associated noncollagenous proteins (BMP/NCP) induce adventitia and adjacent muscle connective-tissue-derived cells to switch from a fibrogenetic to a chondroosteoprogenetic pattern of bone development. The quantity of induced bone is proportional to the dose of BMP/NCP in the range from 10 to 50 mg; immature rabbits produced larger deposits than mature rabbits in response to BMP/NCP. Preoperative local intramuscular injections of citric, edetic, or hyaluronic acids in specified concentrations markedly enhanced subperiosteal BMP/NCP-induced bone formation. The quantity of bovine or human BMP/NCP-induced bone formation in rabbits is also increased by very low-dose immunosuppression but not by bone mineral, tricalcium phosphate ceramic, inorganic calcium salts, or various space-occupying, unspecific chemical irritants. Although composities of BMP/NCP and allogeneic rabbit tendon collagen increased the quantity of bone in a parosteal site, in a heterotopic site the composite failed to induce bone formation. In a parosteal site, the conditions permitting BMP/NCP-induced bone formation develop, and the end product of the morphogenetic response is a duplicate diaphysis. How BMP reactivates the morphogenetic process in postfetal mesenchymal-type adventitial cells persisting in adult periosteum (including adjacent muscle attachments) is not known.

Animals↗