Immunoelectron microscopic localization of Collagen type XV during human mesenchymal stem cells mineralization

Collagen: quantification, biomechanics, and role of minor subtypes in cartilage

Collagen is a ubiquitous biomaterial in vertebrate animals. Although each of its 28 subtypes contributes to the functions of many different tissues in the body, most studies on collagen or collagenous tissues have focussed on only one or two subtypes. With recent developments in analytical chemistry, especially mass spectrometry, significant advances have been made toward quantifying the different collagen subtypes in various tissues; however, high-throughput and low-cost methods for collagen subtype quantification do not yet exist. In this Review, we introduce the roles of collagen subtypes and crosslinks, and describe modern assays that enable a deep understanding of tissue physiology and disease states. Using cartilage as a model tissue, we describe the roles of major and minor collagen subtypes in detail; discuss known and unknown structure-function relationships; and show how tissue engineers may harness the functional characteristics of collagen to engineer robust neotissues.

Collagen XV, a multifaceted multiplexin present across tissues and species

Type XV collagen is a non-fibrillar collagen that is associated with basement membranes and belongs to the multiplexin subset of the collagen superfamily. Collagen XV was initially studied because of its sequence homology with collagen XVIII/endostatin whose anti-angiogenic and anti-tumorigenic properties were subjects of wide interest in the past years. But during the last fifteen years, collagen XV has gained growing attention with increasing number of studies that have attributed new functions to this widely distributed collagen/proteoglycan hybrid molecule. Despite the cumulative evidence of its functional pleiotropy and its evolutionary conserved function, no review compiling the current state of the art about collagen XV is currently available. Here, we thus provide the first comprehensive view of the knowledge gathered so far on the molecular structure, tissue distribution and functions of collagen XV in development, tissue homeostasis and disease with an evolutionary perspective. We hope that our review will open new roads for promising research on collagen XV in the coming years.

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Type XV collagen belongs to the multiplexin subset of the collagen superfamily.

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It is evolutionarily conserved collagen and associated with basement membranes.

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This collagen/proteoglycan hybrid molecule contains an anti-angiogenic restin domain.

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It has important functions in the cardiovascular and the neuromuscular systems.

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Its expression is dysregulated in various diseases including cancers.

Specific concentration of hyaluronan amide derivative induces osteogenic mineralization of human mesenchymal stromal cells: Evidence of RUNX2 and COL1A1 genes modulation

Hyaluronic acid (HA) is an ideal material for tissue regeneration. The aim of this study was to investigate whether a hyaluronan amide derivative (HAD) can enhance the mineralization of human mesenchymal stem cells (hMSCs). Osteogenically induced hMSCs cultured with or without HAD at different concentrations (0.5 mg/ml or 1 mg/ml) were analyzed for mineral matrix deposition, metabolic activity, cellular proliferation, and the expression of 14 osteogenic genes. Unmodified HA (HYAL) was used as control. We demonstrated that only cells treated daily until day 28 with 0.5 mg/ml HAD, but not with 1 mg/ml of HAD and HYAL, showed a significant induction of mineralization at day 14 compared to the osteogenic control group. HAD at both concentrations tested, significantly decreased the expression of the proliferating marker MKI67 at day 2. By contrast, increased metabolic activity was induced only by HYAL from day 14. HAD at both concentrations significantly down modulated SNAI2, DLX5, RUNX2, COL1A1, and IBSP genes, while significantly up regulated COL15A1. The induction of mineralization of 0.5 mg/ml of HAD at day 14 was significantly dependent on a specific modulation of RUNX2 and COL1A1. Our data demonstrate that only 0.5 mg/ml of HAD, but not HYAL, modulated hMSCs osteogenic differentiation, suggesting that the physicochemical features and concentration of HA products could differently affect osteogenic maturation.