The present invention provides compositions comprising an anti-angiogenic factor, and a polymeric carrier. Representative examples of anti-angiogenic factors include Anti-Invasive Factor, Retinoic acids and derivatives thereof, and paclitaxel. Also provided are methods for embolizing blood vessels, and eliminating biliary, urethral, esophageal, and tracheal/bronchial obstructions.

Anti-angiogenic compositions and methods of use

The morbidity associated with autogenous bone graft harvest and the recent concern regarding the transmission of live virus through use of allografts, have been the impetus for research into a variety of materials that could take the place of these standard materials for bone grafting. The positive results reported with various ceramics and/or bone derivatives suggest the possibility of a material with osteoconductive and/or osteoinductive properties for use with or in place of bone graft. This review discusses a variety of bone graft and bone graft substitute materials. Among the osteoconductive materials outlined are the hydroxyapatite and tricalcium phosphate ceramics as well as some reportedly osteoactive polymers. While osteoconduction is a favorable quality, much interest has focussed on the use of osteoinductive or osteogenic materials such as demineralized bone matrix or bone derivatives,that is, BMP, osteogenin, etc. It is increasingly apparent that these materials require a carrier vehicle for optimal expression of osteoactivity. Therefore, the review finishes with a comparison of the various materials suggested for use as carriers.

Bone graft and bone graft substitutes: a review of current technology and applications.

The ability of marrow-derived osteoprogenitor cells to promote repair of critical-size tibial gaps upon autologous transplantation on a hydroxyapatite ceramic (HAC) carrier was tested in a sheep model. Conditions for in vitro expansion of sheep bone marrow stromal cells (BMSC) were established and the osteogenic potential of the expanded cells was validated. Ectopic implantation of sheep BMSC in immunocompromised mice led to extensive bone formation. When used to repair tibial gaps in sheep, cell-loaded implants (n = 2) conducted a far more extensive bone formation than did cell-free HAC cylinders (n = 2) over a 2-month period. In cell-loaded implants, bone formation was found to occur both within the internal macropore space and around the HAC cylinder while in control cell-free implants, bone formation was limited mostly to the outer surface and was not observed in most of the inner pores. As tested in an indentation assay, the stiffness of the complex HAC-bone material was found to be higher in cell-loaded implants compared to controls. Our pilot study on a limited number of large-sized animals suggests that the use of autologous BMSC in conjunction with HAC-based carriers results in faster bone repair compared to HAC alone. Potentially this combination could be used clinically in the treatment of extensive long bone defects.

Autologous bone marrow stromal cells loaded onto porous hydroxyapatite ceramic accelerate bone repair in critical-size defects of sheep long bones.

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

Bone marrow contains osteoblast progenitor cells that can be obtained with aspiration and appear to arise from a population of pluripotential connective-tissue stem cells. When cultured in vitro under conditions that promote an osteoblastic phenotype, osteoblast progenitor cells proliferate to form colonies of cells that express alkaline phosphatase and, subsequently, a mature osteoblastic phenotype. We evaluated the number of nucleated cells in bone-marrow samples obtained with aspiration from the anterior iliac crest of thirty-two patients without systemic disease. There were nineteen male patients and thirteen female patients; the mean age was forty-one years (range, fourteen to seventy-seven years). The prevalence and concentration of the osteoblast progenitor cells also were determined, by placing the bone-marrow-derived cells into tissue-culture medium and counting the number of alkaline phosphatase-positive colony-forming units. In order to assess the effect of aspiration volume, two sequential experiments were performed. In the first experiment, aspiration volumes of one and two milliliters were compared. In the second experiment, aspiration volumes of two and four milliliters were compared. The mean prevalence of alkaline phosphatase-positive colony-forming units in the bone-marrow samples was thirty-six per one million nucleated cells (95 per cent confidence interval, 28 to 47); a mean of 2400 alkaline phosphatase-positive colony-forming units was obtained from a two-milliliter aspirate. There was a significant difference among the patients with respect to the number of alkaline phosphatase-positive colony-forming units in these bone-marrow samples (p < 0.001). Seventy per cent of this variation in the prevalence was due to variation among patients, and 20 per cent was due to variation among aspirates. The number of alkaline phosphatase-positive colony-forming units in the aspirate increased as the aspiration volume increased. However, contamination by peripheral blood also increased as the aspiration volume increased. An increase in the aspiration volume from one to four milliliters caused a decrease of approximately 50 per cent in the final concentration of alkaline phosphatase-positive colony-forming units in an average sample. CLINICAL RELEVANCE: On the basis of these data, we recommend that, when bone marrow is obtained with aspiration for use as a bone graft, the volume of aspiration from any one site should not be greater than two milliliters. A larger volume decreases the concentration of osteoblast progenitor cells because of dilution of the bone-marrow sample with peripheral blood. We estimate that four one-milliliter aspirates will provide almost twice the number of alkaline phosphatase-positive colony-forming units as will one four-milliliter aspirate. In addition, these data confirm that humans differ significantly from one another with respect to the cellularity of bone marrow and the prevalence of osteoblast progenitor cells. Additional studies are necessary to determine if the number or prevalence of alkaline phosphatase-positive colony-forming units in bone marrow is a determining factor in the efficacy of an autogenous bone or bone-marrow graft and to ascertain how the number and function of alkaline phosphatase-positive colony-forming units may change as a function of factors such as age, menopausal status, and selected diseases.

Aspiration to Obtain Osteoblast Progenitor Cells from Human Bone Marrow: The Influence of Aspiration Volume*

Ceramics have many properties which might make them suitable alternatives to bone grafts. This present study was done to find a suitable biodegradable porous ceramic for human bone replacement. Three different porous ceramics (calcium aluminate, calcium hydroxyapatite and tricalcium phosphate), with interlinked pores of two size ranges (150 to 210 micron), were implanted into the skulls of rats and rabbits for up to six months; the interaction with surrounding bone, which is virtually devoid of bone marrow, was then assessed. The ceramics caused no adverse biological response. Tissue ingrowth into pores throughout the implant was seen in all three types and in both pore sizes of ceramic, but the density of the penetrating tissue was far less for calcium aluminate than for calcium hydroxyapatite or tricalcium phosphate. For each type of ceramic, the soft-tissue ingrowth was more dense with the larger pore size, and with a longer period of implantation. Bone ingrowth was not usually seen within the pores of any ceramic. There were no differences in the histological findings between the rats and the rabbits. The results demonstrate that it is possible to produce ceramic materials with a porous structure which allows ingrowth of tissue and biological fluids.

The use of ceramics for bone replacement. A comparative study of three different porous ceramics

Bone ingrowth into three different porous ceramics implanted into the tibia of rats and rabbits.

The ability of four different ceramic materials to support osteogenesis when placed with bone marrow into an intermuscular site was studied. In the search for biodegradable porous ceramic materials that could be used for bone replacement and that would slowly be replaced by bone by means of "creeping substitution," the authors fabricated porous alumina, calcium aluminate, calcium hydroxyapatite, and tricalcium phosphate. Specially shaped compacts, impregnated with autologous bone marrow, were inserted into intermuscular pouches in rabbits and retrieved after 14-182 days. Newly formed bone was found within the contents of the well after 14 days and was visible at all times up to 182 days. The bone was frequently found to have adhered to the ceramic and to have penetrated the interior if the pore size was greater than 100 micron. Further investigation of the use of synthetic materials in bone replacement is warranted due to the finding that some porous ceramic material permit bony ingrowth from autologous marrow cells.

Osteogenesis after bone and bone marrow transplantation. The ability of ceramic materials to sustain osteogenesis from transplanted bone marrow cells: preliminary studies.

The acute childhood diseases haematogenous staphylococcal osteomyelitis and septic arthritis were studied concurrently using avian models which closely resemble the human diseases. Ultrastructural studies during the initial stages of bone and joint infection showed that adherence of bacteria to cartilage, bacterial proliferation, cartilage destruction and subsequent bacterial spread along the vascular channels within cartilage were common to both disease processes. Histological studies revealed that transphyseal blood vessels were present in the growing chickens and were a likely explanation for the frequency of the concurrence of acute osteomyelitis and adjacent joint infection following intravenous injection of bacteria. Transphyseal vessels provide a direct connection between the growth plate (physis) and epiphyseal cartilage supplying a route for bacteria to spread from an osteomyelitic focus in the metaphysis to the epiphysis and subsequently to the joint lumen.

Acute haematogenous osteomyelitis and septic arthritis--a single disease. An hypothesis based upon the presence of transphyseal blood vessels

A simple and reproducible model of acute haematogenous staphylococcal osteomyelitis is described. Twenty-nine day-old chickens were inoculated intravenously with 10(4)-10(8) viable organisms Staphylococcus aureus per kg body weight and were killed 1-8 days after inoculation. Macroscopic septic foci could be detected within 24 hr of inoculation and were most commonly situated in the metaphyseal region of the proximal tibia and distal femur. Lesions in other organs were not observed. The production of osteomyelitis was dependent on the bacterial inoculum size. It was estimated that 5.5 X 10(5) viable organisms per kg body weight of chicken were required to produce osteomyelitis in 50 per cent of injected chickens. Chicken weights were monitored throughout the experiment. A close negative correlation existed between the logarithm of the bacterial inoculum size and the chicken growth rate in the first 24 hr following inoculation (r = -0.968, P less than 0.01). The chicken growth rate was therefore used as an accurate predictor of osteomyelitis in individual chickens.

Sydney Nade

Papers

The use of ceramics for bone replacement. A comparative study of three different porous ceramics

Bone ingrowth into three different porous ceramics implanted into the tibia of rats and rabbits.

Osteogenesis after bone and bone marrow transplantation. The ability of ceramic materials to sustain osteogenesis from transplanted bone marrow cells: preliminary studies.

Acute haematogenous osteomyelitis and septic arthritis--a single disease. An hypothesis based upon the presence of transphyseal blood vessels

Acute haematogenous osteomyelitis: an experimental model.