Expression of receptors for basic fibroblast growth factor on human periodontal ligament cells

The multifaceted role of the vasculature in endochondral fracture repair

Fracture healing is critically dependent upon an adequate vascular supply. The normal rate for fracture delayed or non-union is estimated to be between 10 and 15%, and annual fracture numbers are approximately 15 million cases per year. However, when there is decreased vascular perfusion to the fracture, incidence of impaired healing rises dramatically to 46%. Reduction in the blood supply to the fracture can be the result of traumatic injuries that physically disrupt the vasculature and damage supportive soft tissue, the result of anatomical location (i.e., distal tibia), or attributed to physiological conditions such as age, diabetes, or smoking. The role of the vasculature during repair is multifaceted and changes during the course of healing. In this article, we review recent insights into the role of the vasculature during fracture repair. Taken together these data highlight the need for an updated model for endochondral repair to facilitate improved therapeutic approaches to promote bone healing.

Periodontal fibroblasts modulate proliferation and osteogenic differentiation of embryonic stem cells through production of fibroblast growth factors

BACKGROUND

Periodontal ligament fibroblasts (PLFs) maintain homeostasis of periodontal ligaments by producing paracrine factors that affect various functions of stem-like cells. It is hypothesized that PLFs induce proliferation and differentiation of stem cells more effectively than gingival fibroblasts (GFs) and skin fibroblasts (SFs).

METHODS

PLFs and GFs were isolated from extracted teeth and cultured in the presence and absence of osteogenesis-inducing factors. Mouse embryonic stem (mES) cells and SFs were purchased commercially. mES cells were incubated with culture supernatants of these fibroblasts or cocultured directly with the cells. Proliferation and mineralization in mES cells were determined at various times of incubation. Immunostaining and polymerase chain reaction were performed. The activity of mitogen-activated protein kinase and alkaline phosphatase (ALP) was also measured.

RESULTS

In cocultures, PLFs stimulated proliferation of mES cells more effectively than GFs or SFs. Similarly, the addition of culture supernatant of PLFs induced the most prominent proliferation of mES cells, and this was significantly inhibited by treatment with antibody against fibroblast growth factor (FGF)4 or the c-Jun N-terminal kinase inhibitor SP600125 (anthra[1,9-cd]pyrazol-6(2H)-one). Supplementation with culture supernatant from the fibroblasts induced osteogenic differentiation of mES cells in the order PLFs > GFs > SFs. These activities of PLFs were related to their potential to produce osteogenic markers, such as ALP and runt-related transcription factor-2 (Runx2), and to secrete FGF7. Pretreatment of mES cells with the extracellular signal-regulated kinase inhibitor PD98059 [2-(2-amino-3-methyoxyphenyl)-4H-1-benzopyran-4-one] or SP600125 clearly attenuated mineralization induced by culture supernatant of PLF with attendant decreases in mRNA levels of Runx2, bone sialoprotein, osteocalcin, and osteopontin.

CONCLUSION

PLFs regulate the proliferation and osteogenic differentiation of mES cells more strongly than GFs and SFs via the secretion of FGF through a mechanism that involves mitogen-activated protein kinase-mediated signaling.