Immunoelectron microscopic study of proteoglycans in rat epiphyseal growth plate cartilage after fixation with ruthenium hexamine trichloride (RHT)

The role of macrophages in the tissues regeneration stimulated by the biomaterials

Allogenic grafted tissues are subjected to biodegradation and replaced by the regenerate. To minimize the immune response and improve the rebuilding of tissues there was developed a technology to treat tissues with a cells elimination and dosed out extraction of proteoglycanes (Alloplant. With aim to clarify the role of macrophages in the tissues regeneration resulting implantation the biomaterials 112 rats were injected the allogenic and xenogenic (rabbit's) pulverized biomaterials in the form of suspension. Injections were performed subcutaneously into the animals' back by the base of the tail. The control group (14 rats) were injected a physiologic saline. Animals were killed by ether inhalation on day 2, 4, 7, 14, 30, 90 and 180 and tissue sections were studied by light and electron microscopy. The study showed the key role of the macrophages in resorption of the allogenic biomaterial and formation of the newly-formed tissue. Implantation of the biomaterial induced activity a great number of the mature macrophages, which completely lysed and resorbed the biomaterial particles. Expression TNFalpha was significantly higher whereas expression TGF-beta1 was significantly lower. With xenogenic biomaterial implantation there were less macrophages, their activity was restricted. Macrophages containing large vacuoles with an active endo- and exocytosis were revealed in the allogenic biomaterial implantation and were named 'matrix-forming macrophages'. We may suppose that these macrophages synthesize (or re-synthesize) proteoglycan component of the newly-formed collagen fibers. There was put forward a hypothesis about the two component mechanism of the collagen fibers formation.

Immunoelectron microscopic analysis of chondroitin sulfates during calcification in the rat growth plate cartilage

The proximal growth plate cartilage of rat tibia was fixed in the presence of ruthenium hexamine trichloride (RHT) in order to preserve proteoglycans in the tissue. Quantitative changes of chondroitin sulfates during endochondral calcification were investigated by immunoelectron microscopy using mouse monoclonal antibodies 1-B-5, 2-B-6, and 3-B-3, which recognize unsulfated, 4-sulfated, and 6-sulfated chondroitin sulfates, respectively. The content of chondroitin-4-sulfate in the cartilage matrix increased from the proliferative zone to the calcifying zone, while that of unsulfated chondroitin sulfate decreased. Chondroitin-6-sulfate remained constant from the proliferative zone to the upper hypertrophic zone, then decreased in the calcifying zone. The immunoreaction to each antibody increased conspicuously in the cartilagenous core of metaphysial bone trabeculae. The changes of sulfation in chondroitin sulfate chains of proteoglycans may play an important role in inducing and/or promoting calcification in growth plate cartilage.

Application of cationic probes for the ultrastructural localization of proteoglycans in basement membranes

The application of cationic probes for the ultrastructural detection of proteoglycans in basement membranes is reviewed. Proteoglycans are highly negatively charged macromolecules due to their glycosaminoglycan side chains. The interaction of cationic probes with proteoglycans is of an electrostatic nature. Methods are discussed to increase the specificity of probes for proteoglycans. The use of phthalocyanin-like dyes such as Cuprolinic blue, according to the critical electrolyte concentration method, results in a selective staining of proteoglycans. Enzymatic or chemical digestions, however, should be done to validate the proteoglycan nature of the dye-positive granules/filaments, and to establish the class of proteoglycan. The value of cationic probes in basement membrane research on development and pathology is discussed. The potential for deducting molecular information from the ultrastructural appearance of stained proteoglycans is indicated.