[Effect of hematopoietic and lymphoid cells on the stromal CFU colony formation in rabbit bone marrow cell cultures].

Guinea pig and rabbit bone marrow and splenic cells with increasing cellular density suppress in vitro formation of fibroblast colonies by rabbit bone marrow clonogenic stromal cells. At the same time guinea pig bone marrow and splenic cells produce a stimulating effect on guinea pig bone marrow CFUf, but they are inhibited by rabbit splenocytes, although to a lesser extent than rabbit bone marrow CFUf. Rabbit blood platelets stimulate the growth of bone marrow CFUf of these animals.

[Effects of growth factors on growth of stromal CFU-f in mouse bone marrow cell cultures].

Purified mouse IL-1 at doses 15-100 mu/ml inhibits the growth of stromal clonogenic cells /CFU-f/ both in full bone marrow cell cultures /F-cultures/ and in adherent bone marrow cell cultures /A-cultures/. Rec. human TNF-alpha inhibits growth of these cells at doses greater than 50 u/ml, but stimulates it /in 1.

[Osteogenic stem cells of the bone marrow].

This paper presents literature and author's own data demonstrating that bone marrow contains determined osteogenic precursor cells with high potential to differentiation. They are stem cells of the bone and belong to the stromal cell line of the bone marrow which is histogenetically independent of hemopoietic cells. The paper presents detailed analysis of bone marrow stromal cells (CFUf) as well as of their osteogenic properties and requirements in growth factors.

[The dependence of the formation of stromal CFU-f colonies on the stimulating action of hematopoietic cells].

CFU-f-derived stromal colony formation was accomplished in adherent marrow cell cultures (AMCC) with serum-rich medium. It turned out to require additional stimulation by hemopoietic feeder cells: by irradiated marrow cells and spleen cells if they possess megakaryocytes and platelets or by platelets from the blood. PDGF, EGF and IL-3 did not substitute the colony stimulating activity of feeder cells.

[The humoral nature of the colony-stimulating action of bone marrow cells on stromal colony formation in bone marrow cultures].

In 24 hours adherent marrow cell cultures (AMCC) were represented by single stretched fibroblasts. In non-feeder-supplemented AMCC most of the CFU-f remained single fibroblasts or passed through 1-3 cell doublings [correction of dudlings]. The colony stimulating activity of irradiated marrow cells was found to be diffuse across the Millipore filter, which seems to indicate that haemopoietic marrow cells produce a colony stimulating factor which is required for triggering the CFU-f from the Go-period of the cell cycle into cell proliferation.

[Colony-forming fibroblast precursors of the circulating blood].

Colony-forming fibroblast precursors were detected in circulating blood of adult guinea pigs by CFUf in vitro colony assay. SFU amount to 0.9 +/- 0.

[Osteogenic properties of adhesive cells in Dexter culture of the mouse bone marrow].

Disaggregated cell suspensions obtained by mouse bone marrow fermentative digestion as well as stromal tissue obtained by marrow mild mechanical destruction were explanted. Both methods yield the cultures in which the hematopoiesis duration is comparable with dexter cultures. Adhesive cells from all of these three culture types were resuspended and in the porous gelatin sponges heterotopically transplanted under the kidney capsule of syngenic recipients.

[Bone tissue formation in organ cultures of human bone marrow].

Bone formation in adult human bone marrow organ cultures is described. When culturing marrow fragments, thick bone lamina is formed. It has well-mineralized trabecular bone matrix with bone cells incorporated and is lined with osteoblast-like cells.

[Effect of bone marrow cells on colony-forming stromal cells in guinea pigs and on the proliferation of their cultured descendents].

In the presence of irradiated bone marrow cells the efficiency of stromal colony formation increases from 0.8 +/- 0.2 to 3.

[Dynamics of the mineralization of the ground substance in newly formed bony tissue in organ cultures of mouse bone marrow].

Na-beta-glycerophosphate was added to the organ culture medium of mice marrow fragments. New bone ground substance is formed, its mineralization degree and morphology being highly dependent upon glycerophosphate addition and removal periods. Complete or partial ground substance mineralization occurs, in last case calcium insoluble salts may be found in young apical or in old basal parts only.

[Formation of bone tissue by mouse bone marrow cell suspensions in organ culture].

Adult mouse bone marrow cell suspensions prepared by trypsinization were cultivated in gelatin sponges on millipore filters. When HAWP filters were used, multilayer bone structure was formed. It contained mineralized ground substance, incorporated bone cells and osteoblast layer.

[Clonal nature of fibroblast colonies formed by stromal bone marrow cells in culture].

The clonal nature of CFUf-derived fibroblast colonies was tested in mixed cultures of CBA and CBAT6T6 bone marrow cells. Inoculation of marrow cell suspensions into flasks coated with poly-I-lysin has proved that no stromal aggregates were present among cells subjected to explantation. Marrow cell cultures depleted of macrophages and myeloid cells were used for chromosome analysis.

[Differentiation potentials of clonal strains of bone marrow fibroblasts].

The clonal nature of CFUf-derived fibroblast colonies was proved by chromosomal analysis of individual colonies and single-colony-derived fibroblast strains using mixed cell cultures from male and female rabbits. CFUf progeny, forming colonies composed of more than 10(3) cells was capable of 20-30 cell doublings during subsequent passages. When transplanted in diffusion chambers, single-colony-derived fibroblast strains formed bone and cartilage simultaneously.

[Bone formation in bone marrow organ cultures].

Bone tissue composed of typical bone trabeculae containing ground substance with incorporated osteogenic cells and osteoblast layer was formed in organ cultures of bone marrow obtained from adult mice. Electron microscopic properties of the bone formed in vitro were identical to those of the bone tissue in vivo. The mineralization of the bone took place only in the presence of Na-beta-glycerophosphate in the culture medium.

[Clonogenic stromal cell count in the bone marrow of mice].

The number of fibroblast colonies in bone marrow cultures depends on FCFC concentration in explanted cells and FCFC cloning efficiency. For mouse bone marrow the efficiency of fibroblast colony formation increases in the presence of the feeder (irradiated bone marrow of spleen cells). Colony-stimulating feeder activity does not depend on the presence of phagocytic and stromal cells in the feeder cell population.

[Proliferative and differentiation potentials of skeletogenic bone marrow colony-forming cells].

The clonal nature of bone marrow fibroblast colonies derived from clonogenic bone marrow osteogenic cells (CFUf) was proved by the chromosome analysis. During subsequent passages of multi-colony derived bone marrow fibroblast strains there occurs a pronounced increase in the cell number and in the number of osteogenic units (tested by transplantation in diffusion chambers). Single colony-derived strains are capable of forming bone and cartilage simultaneously.

[Quantitative characteristics of the transfer of the hematopoietic microenvironment].

Heterotopic transplantation of marrow fragments results in the formation of new bone marrow organs. The amount of hemopoietic cells populating these organs is connected nonlinearly with the volume of the grafted tissue or with the number of transplanted marrow cells. Statistical analysis points out that the number of the populating cells depends on the radius of the initial bone marrow transplant.

[A count of osteogenic precursor cells in the bone marrow and their multiplication in cultures].

The progeny of clonogenic stromal medullary fibroblasts from rabbits was cultivated by repeated passage. As a result of several passages the number of cells under consideration could be raised hundreds of thousand times as compared with the initial cell quantity. The strains of stromal medullary fibroblasts were found to have osteogenic properties; during reverse transplantation to the body they formed osseous tissue, creating the medullary organs.

[Properties of bone tissue induced by transitional epithelium].

Bone induction occurs with about 100% frequency around both the auto- and homotransplants of the guinea-pig transitional epithelium. In most cases the bone that developed around the epithelium disappears after immunological resorption of the homotransplanted epithelium. It was found from experiments with the mixed auto- and homological epithelium that the immunological response itself is not responsible for resorption of the induced bone tissue.

[Stromal bone marrow cells and the hematopoietic microenvironment].

Stromal clonogenic fibroblasts of the bone marrow possessing osteogenic potential are responsible for hemopoietic bone marrow microenvironment. These cells may be recovered from the bone marrow by cloning in cell cultures; their progeny cells upon retransplantation into the body form new bone marrow organs. Microenvironmental cells are histogenetically independent of hemopoietic cells.

[Effect of bone marrow trypsinization on the efficiency of fibroblast colony formation in monolayer cultures].

Stromal bone marrow mechanocytes responsible for microenvironment transfer during heterotopic transplantation of hemopoietic tissue from fibroblast clones in monolayer cultures. Fibroblast colony forming cells (FCFC) are readily released from tissue structures together with hemopoietic elements and are contained in bone marrow cell suspension at a concentration of 1 x 10(-5)-10 x 10(-5). Pretreatment with trypsin of bone marrow fragments increases the content of FCFC in bone marrow cell suspension.

[Transfer of bone marrow microenvironment by stromal cells grown in culture and transplanted into sponges].

Monocellular suspensions from trypsinized CBA mouse bone marrow cells were explanted to monolayer cultures. The cells of the adhesive layer withdrawn from 15-30-day cultures were transplanted in gelatin sponges beneath the kidney capsule from syngeneic recipients. The transplantation was accompanied by bone formation and by transfer of bone marrow microenvironment in the overwhelming majority of cases.