Effect of 4-methylumbelliferyl-beta-d-xyloside on collagen synthesis in chick limb bud mesenchymal cell cultures

Platelet-Rich Plasma Promotes Axon Regeneration, Wound Healing, and Pain Reduction: Fact or Fiction

Platelet-rich plasma (PRP) has been tested in vitro, in animal models, and clinically for its efficacy in enhancing the rate of wound healing, reducing pain associated with injuries, and promoting axon regeneration. Although extensive data indicate that PRP-released factors induce these effects, the claims are often weakened because many studies were not rigorous or controlled, the data were limited, and other studies yielded contrary results. Critical to assessing whether PRP is effective are the large number of variables in these studies, including the method of PRP preparation, which influences the composition of PRP; type of application; type of wounds; target tissues; and diverse animal models and clinical studies. All these variables raise the question of whether one can anticipate consistent influences and raise the possibility that most of the results are correct under the circumstances where PRP was tested. This review examines evidence on the potential influences of PRP and whether PRP-released factors could induce the reported influences and concludes that the preponderance of evidence suggests that PRP has the capacity to induce all the claimed influences, although this position cannot be definitively argued. Well-defined and rigorously controlled studies of the potential influences of PRP are required in which PRP is isolated and applied using consistent techniques, protocols, and models. Finally, it is concluded that, because of the purported benefits of PRP administration and the lack of adverse events, further animal and clinical studies should be performed to explore the potential influences of PRP.

Involvement of a chondroitin sulfate proteoglycan in the avoidance of chick epidermis by dorsal root ganglia fibers: a study using beta-D-xyloside

In 7-day chick embryo dorsal root ganglia and epidermis cocultures, nerve fibers avoid the epidermis. Previous studies have indicated that glycoproteic factors, secreted by epidermis, could be involved in this phenomenon. Treatment of epidermis by beta-D-xyloside, a specific proteoglycan synthesis inhibitor, abolishes the avoidance reaction. The same result is obtained when anti-chondroitin sulfate antibodies are added to the culture medium. Using HPLC and 35SO4 labeling combined with chondroitinase and hyaluronidase treatment, it has been demonstrated that chondroitin sulfate is present in the epidermal conditioned medium. This suggests that a chondroitin sulfate proteoglycan secreted by the epidermis is implicated in the neurite avoidance reaction and that epidermis could therefore control its own "noninnervation". In vivo, inhibitory influences by local extracellular components may control the guidance of growth cones during nerve pattern formation.

Mesenchymal stem cells

Bone and cartilage formation in the embryo and repair and turnover in the adult involve the progeny of a small number of cells called mesenchymal stem cells. These cells divide, and their progeny become committed to a specific and distinctive phenotypic pathway, a lineage with discrete steps and, finally, end-stage cells involved with fabrication of a unique tissue type, e.g., cartilage or bone. Local cuing (extrinsic factors) and the genomic potential (intrinsic factors) interact at each lineage step to control the rate and characteristic phenotype of the cells in the emerging tissue. The study of these mesenchymal stem cells, whether isolated from embryos or adults, provides the basis for the emergence of a new therapeutic technology of self-cell repair. The isolation, mitotic expansion, and site-directed delivery of autologous stem cells can govern the rapid and specific repair of skeletal tissues.

Extracellular matrix (ECM) proteoglycans produced by cultured bovine corneal endothelial cells

The nature of the proteoglycan(s) (PG) found in the extracellular matrix (ECM) layer produced by cultured bovine corneal endothelial (BCE) cells is analyzed. The PG(s) account for approximately 5 to 6% of the dry weight of the ECM, regardless of the amount of extracellular soluble PG available in the medium. A 4 M guanidinium chloride (GuCl) extract of ECM was separated on a dissociative cesium chloride (CsCl) gradient (1.25 g/cm3 starting density). Results showed one main peak of PG substance(s) comprising 91% of the total labelled substance and uronic acid, banding at a specific buoyant density of 1.29 g/cm3. The molecular weight of this major PG(s) as estimated by gel filtration on Sepharose CL-4B ranged from 0.5 to 0.7 X 10(6). Further chemical analysis of the main PG(s) band revealed a protein moiety accounting for 45% of the weight and carbohydrates-glycosaminoglycans (GAG) accounting for the remaining 55%. Analysis of the GAG chains (over the entire gradient) showed a composition, based on the susceptibility of the PG substance(s) to degrading enzymes, of 50% heparan sulfate, 43.5% dermatan sulfate, and 6.5% chondroitin 4- and 6-sulfate chains. BCE cell cultures grown in the presence of beta-D-xyloside produced an ECM lacking more than 90% of the GAG content found in the control ECM. The medium-soluble GAG chains, produced in vast excess in cultures grown in the presence of beta-D-xyloside, are composed mainly of chondroitin 4- and 6-sulfates.