Under the visuals of scanning electron microscopy (SEM), the red color in the slides that are stained by Masson/Trichrome indicates lamellar and remodeled bone, while the blue color shows freshly deposited and immature bone. For each hematoxylin/eosin-stained cross-section, 3 or 4 images (adequate to fill the construct cross-sections) are required to calculate the bone tissue area and available area for tissue ingrowth (net implant area - undegraded scaffold area) by digital imaging analysis. The samples are stained with hematoxylin/eosin and Masson/Trichrome, and both a qualitative exam for the presence of bone tissue and a quantitative exam by computerized bone histomorphometry is conducted. The samples are deposited in paraffin, and the cross-sections of the samples are prepared with 5 um thickness at three different strata. įinal visualization of osteoprogenitor cells under the microscope involves a delicate preparation phase: the explants are fixed in 4% buffered formalin for one whole day, and samples are decalcified with 0.5 mol/L ethylenediaminetetraacetic acid (pH 8) for 7 to 10 days. These osteoprogenitors hyper-regulate bone morphogenetic proteins during differentiation into mature osteoblasts responsible for the production of bone matrix. Osteoprogenitor cells also reside in the perichondrium. Proline-rich tyrosine kinase 2 supposedly regulates the differentiation of early osteoprogenitors, and proline-rich tyrosine kinase 2 inhibitors promote osteogenesis and could act as a treatment for osteoporosis. Neuropeptide Y is a potent regulator of osteogenesis, and recent studies have confirmed that osteoprogenitor cells originating from hypothalamic Y2-/- mice have enhanced osteogenic activities. The endocrine system and local factors (growth factors and cytokines) mainly regulate osteogenesis. After completing DNA synthesis and cell expansion, the cell retains its original genetic information. Osteoprogenitor cells can differentiate into osteoblasts through mitotic division or by dividing into two stem cells via a highly regulated mechanism, which remains static during the proliferation process. They participate in osteogenic differentiation and play a role in regulating angiogenesis. Osteoprogenitors can self-proliferate and self-renew.
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