Supplementation of growth differentiation factor-5 increases proliferation and size of chondrogenic pellets of human umbilical cord-derived perivascular stem cells

Gestational Diabetes Affects the Growth and Functions of Perivascular Stem Cells

Gestational diabetes mellitus (GDM), one of the common metabolic disorders of pregnancy, leads to functional alterations in various cells including stem cells as well as some abnormalities in fetal development. Perivascular stem cells (PVCs) have gained more attention in recent years, for the treatment of various diseases. However, the effect of GDM on PVC function has not been investigated. In our study, we isolated PVCs from umbilical cord of normal pregnant women and GDM patients and compared their phenotypes and function. There is no significant difference in phenotypic expression, response to bFGF exposure and adipogenic differentiation capacity between normal (N)-PVCs and GDM-PVCs. However, when compared with N-PVCs, early passage GDM-PVCs displayed decreased initial rates of cell yield and proliferation as well as a reduced ability to promote wound closure. These results suggest that maternal metabolic dysregulation during gestation can alter the function of endogenous multipotent stem cells, which may impact their therapeutic effectiveness.

The Good the Bad and the Ugly of Glycosaminoglycans in Tissue Engineering Applications

High sulfation, low cost, and the status of heparin as an already FDA- and EMA- approved product, mean that its inclusion in tissue engineering (TE) strategies is becoming increasingly popular. However, the use of heparin may represent a naïve approach. This is because tissue formation is a highly orchestrated process, involving the temporal expression of numerous growth factors and complex signaling networks. While heparin may enhance the retention and activity of certain growth factors under particular conditions, its binding 'promiscuity' means that it may also inhibit other factors that, for example, play an important role in tissue maintenance and repair. Within this review we focus on articular cartilage, highlighting the complexities and highly regulated processes that are involved in its formation, and the challenges that exist in trying to effectively engineer this tissue. Here we discuss the opportunities that glycosaminoglycans (GAGs) may provide in advancing this important area of regenerative medicine, placing emphasis on the need to move away from the common use of heparin, and instead focus research towards the utility of specific GAG preparations that are able to modulate the activity of growth factors in a more controlled and defined manner, with less off-target effects.

Expression of Ion Channels in Perivascular Stem Cells derived from Human Umbilical Cords

Potassium channels, the largest group of pore proteins, selectively regulate the flow of potassium (K⁺) ions across cell membranes. The activity and expression of K⁺ channels are critical for the maintenance of normal functions in vessels and neurons, and for the regulation of cell differentiation and maturation. However, their role and expression in stem cells have been poorly understood. In this study, we isolated perivascular stem cells (PVCs) from human umbilical cords and investigated the expression patterns of big-conductance Ca²⁺-activated K⁺ (BK_Ca) and voltage-dependent K⁺ (K_v) channels using the reverse transcription polymerase chain reaction. We also examined the effect of high glucose (HG, 25 mM) on expression levels of BK_Ca and K_v channels in PVCs. K_Ca1.1, K_Caβ₃, K_v1.3, K_v3.2, and K_v6.1 were detected in undifferentiated PVCs. In addition, HG treatment increased the amounts of BK_Caβ_3a, BK_Caβ₄, K_v1.3, K_v1.6, and K_v6.1 transcripts. These results suggested that ion channels may have important functions in the growth and differentiation of PVCs, which could be influenced by HG exposure.

Paracrine influence of human perivascular cells on the proliferation of adenocarcinoma alveolar epithelial cells

Understanding the crosstalk mechanisms between perivascular cells (PVCs) and cancer cells might be beneficial in preventing cancer development and metastasis. In this study, we investigated the paracrine influence of PVCs derived from human umbilical cords on the proliferation of lung adenocarcinoma epithelial cells (A549) and erythroleukemia cells (TF-1α and K562) in vitro using Transwell® co-culture systems. PVCs promoted the proliferation of A549 cells without inducing morphological changes, but had no effect on the proliferation of TF-1α and K562 cells. To identify the factors secreted from PVCs, conditioned media harvested from PVC cultures were analyzed by antibody arrays. We identified a set of cytokines, including persephin (PSPN), a neurotrophic factor, and a key regulator of oral squamous cell carcinoma progression. Supplementation with PSPN significantly increased the proliferation of A549 cells. These results suggested that PVCs produced a differential effect on the proliferation of cancer cells in a cell-type dependent manner. Further, secretome analyses of PVCs and the elucidation of the molecular mechanisms could facilitate the discovery of therapeutic target(s) for lung cancer.

Growth Differentiation Factor 5-Mediated Enhancement of Chondrocyte Phenotype Is Inhibited by Heparin: Implications for the Use of Heparin in the Clinic and in Tissue Engineering Applications

The highly sulfated glycosaminoglycan (GAG) heparin is widely used in the clinic as an anticoagulant, and researchers are now using it to enhance stem cell expansion/differentiation protocols, as well as to improve the delivery of growth factors for tissue engineering (TE) strategies. Growth differentiation factor 5 (GDF5) belongs to the bone morphogenetic protein family of proteins and is vital for skeletal formation; however, its interaction with heparin and heparan sulfate (HS) has not been studied. We identify GDF5 as a novel heparin/HS binding protein and show that HS proteoglycans are vital in localizing GDF5 to the cell surface. Clinically relevant doses of heparin (≥10 nM), but not equivalent concentrations of HS, were found to inhibit GDF5's biological activity in both human mesenchymal stem/stromal cell-derived chondrocyte pellet cultures and the skeletal cell line ATDC5. We also found that heparin inhibited both GDF5 binding to cell surface HS and GDF5-induced induction of Smad 1/5/8 signaling. Furthermore, GDF5 significantly increased aggrecan gene expression in chondrocyte pellet cultures, without affecting collagen type X expression, making it a promising target for the TE of articular cartilage. Importantly, this study may explain the variable (and disappointing) results seen with heparin-loaded biomaterials for skeletal TE and the adverse skeletal effects reported in the clinic following long-term heparin treatment. Our results caution the use of heparin in the clinic and in TE applications, and prompt the transition to using more specific GAGs (e.g., HS derivatives), with better-defined structures and fewer off-target effects.

Expression of tenocyte lineage-related factors from tonsil-derived mesenchymal stem cells

Human palatine tonsil-derived mesenchymal stem cells (TMSCs) are known to be a new source of progenitor cells. Using waste tissue after tonsillectomy as a cell provider can be the biggest benefit of TMSCs, compared with other stem cells. The purpose of this study was to investigate tenogenic differentiation of TMSCs and to access the differential effects of transforming growth factor beta 3 (TGF-β3) on the tenogenesis of TMSCs. Human tonsil was obtained after tonsillectomy. Using a cytometric analysis, we were able to find that the TMSCs had typical mesenchymal stem cell markers: positive for CD73, CD90, and CD105, and negative for CD14, CD34, and CD45. Using TGF-β3, the expressions of tenocyte-specific genes and proteins, such as collagen type 1 (COL1), tenomodulin (TNMD), and scleraxis (SCX), were measured by a quantitative polymerase chain reaction (PCR), immunofluorescence staining, immunohistochemistry and Western blot analyses. Quantitative PCR assay showed that TGF-β3 significantly increased the expressions of tenocyte lineage marker genes, including COL1, TNMD, and SCX, at a 3-day treatment, compared with control. However, these increases were not found at long-term exposures (7 or 10 days), except that TNMD expression was maintained at 50 ng/mL at a 7-day exposure to TGF-β3. Like genes, the protein expression levels of COL1, TNMD, and SCX were also induced in TGF-β3-treated TMSCs in a 3-day treatment, which were maintained for 10 days, as evidenced by immunofluorescence staining, immunohistochemistry and Western blot analyses. This study demonstrated that TMSCs in tenogenic stimulation with TGF-β3 have a high tenogenic differentiation potential.