PubMed · 4689361
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R J Kones. 1973. Capillary endothelium and data processing: a hypothesis.. https://doi.org/10.1353/pbm.1973.0024
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Endothelial cell differentiation into capillary structures is a complex process that requires the concerted effects of several extracellular matrix proteases, including plasminogen activators. Here, the role of tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) was evaluated in an in vitro model of endothelial morphogenesis involving organization of human umbilical vein endothelial cells into tubular structures when they are cultured on the basement membrane preparation, Matrigel. Both uPA and tPA were detected in HUVEC cultures on Matrigel, and inhibitors of plasminogen activators or of serine proteases decreased the extent of the tube network formed by the cells. The decrease resulting from serine protease inhibitors was additive to that from matrix metalloproteinase inhibitors which have previously been shown to decrease tube formation in this model, suggesting that the two classes of proteases modulate tube formation by distinct mechanisms. Plasminogen activator inhibitor (PAI)-1 decreased tube formation by 50% when added up to 4.5 h after the initiation of an 18 h assay and caused 25% inhibition when added 9.5 h after culture initiation, indicating that the effects of plasminogen activators are not limited to an early event in the differentiation process. Steady-state expression of mRNA for uPA increased during the first several hours of culture on Matrigel, further supporting a role for PA activity throughout the process of tube formation. These findings suggested that PAs may affect multiple events during tube-forming activity. A fucosylated peptide comprising the amino-terminal domain of uPA that binds to the uPA receptor (uPAR) but lacking proteolytic activity enhanced tube formation. In contrast, a defucosylated form of the same peptide had no effect. Since fucosylation of this fragment has been shown to be essential in other models of cell stimulation by uPA-uPAR interaction, these data support the hypothesis that uPA enhances endothelial morphogenesis both through proteolytic activity and via uPAR occupancy. Plasminogen activators could facilitate angiogenesis in vivo.
The vascular density of benign prostatic hyperplasia (BPH) has not been characterized. Previously we reported vessel density (vv/mm2) in prostatic carcinoma was twice that of normal prostate [Bigler et al.: Hum Pathol 24:220-226 1993]. To further characterize vessel density in benign prostate tissue we examined 15 cases of BPH obtained by open prostatectomy. Vessels were stained with antibodies to Factor VIII-related antigen, and vessel density was measured using computer-assisted image analysis. Vessel density was analyzed between various histologic tissue types. Mean vessel density in all transition zone tissue was 70.2 vv/mm2. Vessel density in epithelial hyperplastic nodules (mean 99.3, SD 40.7) exhibited density levels similar to those found in prostatic carcinoma (mean 101.4, SD 35.6). Vessel density in epithelial nodules was significantly higher than in non-nodular epithelial tissue (mean 76.7, SD 23.1; P < 0.001, ratio = 1.3). Higher vessel densities were found in hypercellular stromal nodules (mean 64.7, SD 19.1) than in adjacent stromal areas (mean 36.5, SD 15.3; P < 0.001, ratio = 1.8). Overall, vessel density in BPH was higher than previously found in benign tissue measured in radical prostatectomy specimens, especially in areas of nodular morphology.