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Over the last decade, there has been an increasing interest among researchers for human mesenchymal stromal cells (MSC). Their regenerative properties, multilineage differentiation capacity and immunomodulatory properties make them promising candidates for treatment in various conditions. Emerging biotechnology companies specialized in cellular and regenerative therapies have been focusing their interest on MSC-based therapies, and their use in clinical trials has steadily increased. Notably, MSC are currently tested in clinical trials addressing unmet medical needs in the field of bone fracture repair and more specifically in non-union and delayed union fractures where the bone repair process is impaired. Although MSC can be isolated from various tissues, the most commonly studied sources are bone marrow (BM) and adipose tissue (Ad). In this article, we reviewed the literature directly comparing BM- and Ad-MSC for their in vitro characteristics and in vivo osteogenic potential to determine which source of MSC would be more appropriate for bone fracture repair. As considerable variations in experimental settings between studies were found, our review was based on studies meeting specific sets of criteria, notably regarding donors’ age and gender. This review of side-by-side comparisons suggests that while BM-and Ad-MSC share common general characteristics, BM-MSC have a higher intrinsic osteogenic capacity in vitro and bone repair potential in vivo.

Calretinin immunoreactivity was localized during chick embryonic cervical spine development from day 4 until day 16. A transitory expression of calretinin could be seen from embryonic day 5 to embryonic day 15 in the mesenchymal cells forming the intervertebral disc. Calretinin was most abundant at embryonic day 8 when a maximal proliferation of cells occurred. At embryonic day 12, calretinin positive fibroblasts were located along the fibers forming the annulus fibrosus. At embryonic day 16, calretinin immunoreactivity could no more be detected in the cervical column. In conclusion, an intracellular calcium binding proteins belonging to the calmodulin/troponin C superfamily, appeared to be a marker for the disc formation.

In pineal gland, melatonin is synthesized in pinealocytes. Pharmacological studies using calmodulin antagonists suggested that melatonin synthesis was regulated through calmodulin. However, immunohistochemical studies showed that calmodulin could only be detected in pineal glial cells, and not in pinealocytes. To further investigate this discrepancy, we have tried to detect calmodulin not seen by immunohistochemical methods. We have used rat and chicken pineal homogenate supernatants and Triton X-100-treated pellets denatured by sodium dodecyl sulfate, subjected to electrophoresis and immunoblotting using anti-calmodulin antibodies. Two different IgG (#465 and #860) purified from anti-calmodulin sera were used. In rat pineal homogenate supernatants, calmodulin could be detected by immunoblotting using both antibodies. Some calmodulin could also be detected in the Triton-treated pellet fractions, but no additional cross-reacting bands were detected. However, in both chicken pineal homogenate supernatants and Triton-extracted pellets, in addition to a calmodulin immunoreactive band, two other proteins with approximate molecular masses (M(r)) of 56 kDa and 60 kDa were detected using anti-calmodulin #465. For comparison, similar immunoblot experiments were performed for detection of calbindin-D28K and calretinin, two other calcium binding proteins expressed in different pineal cell populations. Interestingly, Triton extraction of chicken pineal pellets revealed additional bands cross-reacting with each antibody. Anti-calbindin-D28K cross-reacted strongly with a M(r) = 68 kDa protein and weakly with a M(r) = 56 kDa protein. Anti-calretinin cross-reacted strongly with a M(r) = 93 kDa protein and weakly with a M(r) = 56 kDa protein.