Secretion of Hematopoietic Niche Signal Molecules under Conditions of Osteogenic Differentiation of Multipotent Mesenchymal Stromal Cells Induced By Relief Calcium Phosphate Coating

Abstract

Using a multiplex kit the secretion of a number of cytokines, chemokines, and growth factors has been investigated in vitro in a culture of human adipose-derived multipotent mesenchymal stromal cells (hAMMSCs) under conditions of their osteogenic differentiation caused by 14-day contact with a calcium phosphate (CP) surface of different roughness. Bilateral X-ray amorphous CP coatings were prepared on the samples of commercially pure titanium in the anodal regime using a microarc method. The electrolyte consisted of aqueous orthophosphoric acid (20 wt %), calcium carbonate (9 wt %), and synthetic hydroxyapatite nanopowder (6 wt %, particle diameter of 10–30 nm with single agglomerates up to 100 nm). hAMMSCs isolated from lipoaspirate were co-cultured after 4 passages with the CP-coated samples at a final concentration of 1.5 × 105 viable karyocytes per 1.5 mL of standard nutrition medium (without osteogenic stimulators) for 14 days (determination of the [CD45,34,14,20], CD73, CD90, and CD105 cell immunophenotype; analysis of secretory activity) and 21 days (alizarin red S cell culture staining) with medium replacement every 3–4 days. Under conditions of in vitro contact with rough CP coating hAMMSCs differentiated into osteoblasts synthesizing the mineralized bone matrix; this was accompanied by a 2−3-fold increase in the proportion of [CD45,34,14,20]+ hemopoietic cells. The following humoral factors of hemopoietic niches acted as the signal molecules escalating in vitro the hemopoietic base in 14 days of differentiating three-dimensional culture of hAMMSCs: leukemia inhibitory factor (LIF) and stem cell factor (SCF) cytokines in the case of the mean index of CP roughness Ra = 2.4–2.6 µm or stromal derived factor-1 (SDF-1α, CXCL12 chemokine) in the case of Ra = 3.1–4.4 µm.