Supplementation Of Cell Culture Medium Research Articles

Stimulation of osteogenesis and angiogenesis of hBMSCs by delivering Si ions and functional drug from mesoporous silica nanospheres

Multifunctional bioactive materials with the ability to stimulate osteogenesis and angiogenesis of stem cells play an important role in the regeneration of bone defects. However, how to develop such biomaterials remains a significant challenge. In this study, we prepared mesoporous silica nanospheres (MSNs) with uniform sphere size (∼90nm) and mesopores (∼2.7nm), which could release silicon ions (Si) to stimulate the osteogenic differentiation of human bone marrow stromal cells (hBMSCs) via activating their ALP activity, bone-related gene and protein (OCN, RUNX2 and OPN) expression. Hypoxia-inducing therapeutic drug, dimethyloxaloylglycine (DMOG), was effectively loaded in the mesopores of MSNs (D-MSNs). The sustained release of DMOG from D-MSNs could stabilize HIF-1α and further stimulated the angiogenic differentiation of hBMSCs as indicated by the enhanced VEGF secretion and protein expression. Our study revealed that D-MSNs could combine the stimulatory effect on both osteogenic and angiogenic activity of hBMSCs. The potential mechanism of D-MSN-stimulated osteogenesis and angiogenesis was further elucidated by the supplementation of cell culture medium with pure Si ions and DMOG. Considering the easy handling characteristics of nanospheres, the prepared D-MSNs may be applied in the forms of injectable spheres for minimally invasive surgery, or MSNs/polymer composite scaffolds for bone defect repair. The concept of delivering both stimulatory ions and functional drugs may offer a new strategy to construct a multifunctional biomaterial system for bone tissue regeneration.

Tyrosine isomers and hormonal signaling: A possible role for the hydroxyl free radical in insulin resistance.

Oxidative stress processes play a major role in the development of the complications associated with diabetes and other diseases via non-enzymatic glycation, the hexosamine pathway, the polyol pathway and diacylglycerol-protein kinase C. Oxidative stress may lead to the production of hydroxyl free radicals, which can attack macromolecules, such as lipids, nucleic acids or amino acids. Phenylalanine (Phe) can be enzymatically converted to the physiological para-tyrosine (p-Tyr); however, a hydroxyl free radical attack on Phe may yield meta- and ortho-tyrosine (m- and o-Tyr, respectively) in addition to p-Tyr. Hence, m- and o-Tyr may be regarded as markers of hydroxyl free radical-induced damage. Their accumulation has been described; e.g., this accumulation has been found in the urine of patients with diabetes mellitus (DM) and/or chronic kidney disease, in cataract lenses, in vessel walls, in irradiated food and in amniotic fluid, and it may serve as an indicator of oxidative stress. The use of resveratrol to treat patients with type 2 DM led to a decrease in the urinary excretion of o-Tyr and concomitantly led to an improvement in insulin signaling and insulin sensitivity. Literature data also suggest that m- and o-Tyr may interfere with intracellular signaling. Our group has shown that erythropoietin (EPO) has insulin-like metabolic effects on fat cells in addition to its ability to promote the proliferation of erythroid precursor cells. We have shown that the supplementation of cell culture medium with m- and o-Tyr inhibits erythroblast cell proliferation, which could be ameliorated by p-Tyr. Additionally, in vivo, the o-Tyr/p-Tyr ratio is higher in patients with renal replacement therapy and a greater need for EPO. However, the o-Tyr/p-Tyr ratio was an independent determinant of EPO-resistance indices in our human study. The o-Tyr content of blood vessel walls inversely correlates with insulin- and acetylcholine-induced vasodilation, which could be further impaired by artificial oxidative stress and improved by the use of antioxidants. In rats that receive o-Tyr supplements, decreased vasorelaxation is detected in response to insulin. Additionally, o-Tyr supplementation led to the incorporation of the unnatural amino acid into cellular proteins and caused a decrease in the insulin-induced phosphorylation of endothelial nitric oxide synthase. Our data suggest that m- and o-Tyr may not only be markers of oxidative stress; instead, they may also be incorporated into cellular proteins, leading to resistance to insulin, EPO and acetylcholine.

Biological activity of a standardized freeze-dried platelet derivative to be used as cell culture medium supplement

Serum of animal origin and in particular fetal bovine serum is the most commonly utilized cell culture medium additive for in vitro cell growth and differentiation. However, several major concerns have been raised by the scientific community regarding the use of animal sera for human cell-based culture applications. Among the possible alternatives to the animal serum, platelet-derived compounds have been proposed since more than 10 years. Nevertheless, the high degree of variability between the different platelet preparations, and the lack of standardized manufacturing and quality control procedures, made difficult to reach a consensus on the applicability of this novel cell culture medium supplement. In this study, we describe the preparation of a standardized platelet-rich plasma (PRP) derivative obtained starting from human-certified buffy coat samples with a defined platelet concentration and following protocols including also freeze-drying, gamma irradiation and biological activity testing prior the product release as cell culture medium additive. Biological activity testing of the different preparations was done by determining the capability of the different PRP preparations to sustain human bone marrow mesenchymal stem cell (MSC) clone formation and proliferation. Taking advantage of a developed MSC in vitro clonogenicity test, we also determined biological activity and stability of the freeze-dried gamma-sterilized PRP preparations after their storage for different times and at different temperatures. The PRP effects on cell proliferation were determined both on primary cell cultures established from different tissues and on a cell line. Results were compared with those obtained in “traditional” parallel control cultures performed in the presence of bovine serum [10% fetal calf serum (FCS)]. Compared to FCS, the PRP addition to the culture medium increased the MSC colony number and average size. In primary cell cultures and in cell line cultures, the PRP promoted cell proliferation also in conditions where the FCS had not a proliferation stimulating effect due to either the nature of the cells and the tissue of origin (such as human articular chondrocytes from elderly patients) or to the critical low density cell seeding (such as for HeLa cells). In summary, the standardized PRP formulation would provide an “off-the-shelf” product to be used for the selection and expansion of several cell types also in critical cell culture conditions.

Expansion and differentiation of human primary osteoblasts in two- and three-dimensional culture

Despite the regenerative capability of bone, treatment of large defects often requires bone grafts. The challenge for bone grafting is to establish rapid and sufficient vascularization. Three-dimensional (3D) multicellular spheroids consisting of the relevant cell types can be used as “mini tissues” to study the complexity of angiogenesis. We investigated two-dimensional (2D) expansion, differentiation and characterization of primary osteoblasts as steps toward the establishment of 3D multicellular spheroids. Supplementation of cell culture medium with vitamin D3 induces the osteocalcin expression of osteoblasts. An increased osteocalcin concentration of 10.8 ± 0.58 ng/ml could be measured after 19 days in supplemented medium. Vitamin D3 has no influence on the expression of alkaline phosphatase or the deposition of calcium. Expression of these additional osteogenic markers requires addition of a cocktail of osteogenic factors that, conversely, have no influence on the expression of osteocalcin. Supplementation of the cell culture medium with both vitamin D3 and a cocktail of osteogenic factors is recommended to produce an osteoblast phenotype that secretes osteocalcin, expresses alkaline phosphatase and deposits calcium. In such a supplemented medium, a mean osteocalcin concentration of 11.63 ± 4.85 ng/ml was secreted by the osteoblasts. Distinguishing osteoblasts and fibroblasts remains a challenge. Neither differentiated nor undifferentiated osteoblasts can be distinguished from fibroblasts by the expression of CD90, ED-A-fibronectin or α-smooth muscle actin; however, these cell types exhibit clear differences in their growth characteristics. Osteoblasts can be arranged as 3D spheroids by coating the bottom of the cell culture device with agarose. The cellular composition of 3D multicellular spheroids can be evaluated quantitatively using vital fluorescence labeling techniques. Spheroids are a promising tool for studying angiogenic and osteogenic phenomena in vivo and in vitro.

Development of poly(l-lactic acid) hollow fiber membranes for artificial vasculature in tissue engineering scaffolds

In tissue engineering constructs, vascularization within in vitro cultured tissue is one of the major problems, as proliferating cells act themselves as a barrier for mass transfer. Issues related especially to nutrient and oxygen delivery to the cells limit tissue construct development to smaller than clinically relevant dimensions, which in-turn limits the ability for in vivo integration. In this work, we develop highly permeable biodegradable poly (l-lactic acid) (PLLA) hollow fibers (HF) which when integrated with tissue engineered scaffolds in vitro can improve nutrient supply to the cells. In fact, we study various fiber spinning parameters to develop the optimum fiber structure. By using 1,4 dioxane as solvent and ethanol as non-solvent at very low temperature (−6°C), we develop fibers with thin dense top-layer and spongy sub-layer. Porogens like poly-vinylpyrrolidone (PVP) and poly (ethylene-glycol) (PEG) are added to the dope solution. Subsequent treatment with sodium hypochlorite produces open fiber surface and increased pore interconnectivity. The produced fibers have good mechanical properties. The transport of bovine serum albumin (BSA) and of cell culture medium supplement with 10% fetal bovine serum (FBS) through the produced PLLA fiber is high (permeance 1963L/(m2hbar)) with low protein retention. In vitro static and dynamic cell culturing for 3 and 7 days using mouse pre-myoblast (C2C12) cells suggests that the fabricated PLLA hollow fibers are suitable for delivery of nutrients to the cells in a tissue engineering scaffold.

Effects of Resin or Charcoal Treatment on Fetal Bovine Serum and Bovine Calf Serum

Introduction. Charcoal- or resin-stripping of fetal bovine serum (FBS) or bovine calf serum (BCS) intended for supplementation of cell culture media is widely practiced to remove a variety of endogenous compounds, including steroid, peptide, and thyroid hormones. The possibility that stripping removes other biologically relevant factors from serum may not be appreciated. Methods. In this report, standardized clinical laboratory testing methods were used to assess the effects of resin- and charcoal-stripping on content in FBS and BCS of more than 25 analytes in the sera. Results and Conclusion. In addition to hormones, the serum constituents affected by stripping are certain vitamins, electrolytes, enzyme activities, and metabolites.

Glutathione Peroxidase 2 Inhibits Cyclooxygenase-2–Mediated Migration and Invasion of HT-29 Adenocarcinoma Cells but Supports Their Growth as Tumors in Nude Mice

The selenoprotein gastrointestinal glutathione peroxidase 2 (GPx2) is up-regulated in a variety of cancer cells with thus far unknown consequences. Therefore, two clones of a human colon cancer cell line (HT-29) in which GPx2 was stably knocked down by small interfering RNA (siRNA; siGPx2) were used to test whether cancer-relevant processes are affected by GPx2. The capacity to grow anchorage independently in soft agar was significantly reduced in siGPx2 cells when compared with controls (i.e., HT-29 cells stably transfected with a scramble siRNA). The weight of tumors derived from siGPx2 cells injected into nude mice was lower in 9 of 10 animals. In contrast, in a wound-healing assay, wound closure was around 50% in controls and 80% in siGPx2 cells, indicating an enhanced capacity of the knockdown cells to migrate. Similarly, invasion of siGPx2 cells in a Transwell assay was significantly increased. Migration and invasion of siGPx2 cells were inhibited by celecoxib, a cyclooxygenase-2 (COX-2)-specific inhibitor, but not by alpha-tocopherol. Selenium supplementation of cell culture medium did not influence the results obtained with siGPx2 cells, showing that none of the other selenoproteins could replace GPx2 regarding the described effects. The data show that GPx2 inhibits malignant characteristics of tumor cells, such as migration and invasion, obviously by counteracting COX-2 expression but is required for the growth of transformed intestinal cells and may, therefore, facilitate tumor cell growth. The data also shed new light on the use of selenium as a chemopreventive trace element: a beneficial effect may depend on the stage of tumor development.

Specific Labeling of Isoprenylated Proteins: Application to Study Inhibitors of the Post-translational Farnesylation and Geranylgeranylation

Specific labeling of either farnesylated or geranylgeranylated proteins in human PC-3 prostate cancer cell line was obtained by suppression of mevalonic acid biosynthesis with lovastatin, 50 μM, followed by supplementation of cell culture medium with either [3H]farnesyl- or [3H]geranylgeranyl-pyrophosphate. The immunoprecipitation of either a farnesylated (p21 ras) or geranylgeranylated (p21 rap 1) protein demonstrated that labeling was specific since proteins were detected only if the appropriate isoprenoid was added to the culture medium. TLC analysis indicated that no conversion of one isoprenoid to the other occurred in these conditions. The selective labeling of either farnesylated or geranylgeranylated proteins may be a valuable tool for the development of inhibitors of isoprenoid transferases as a potential new class of antitumor agents.

Replication of duck hepatitis B virus in primary duck hepatocytes and its dependence on the state of differentiation of the host cell.

Primary duck hepatocytes obtained from Pekin ducks congenitally infected with duck hepatitis B virus were used to monitor expression of viral proteins and replication of viral DNA in cell culture. Duck hepatitis B virus core antigen, duck hepatitis B virus pre-surface antigen and duck hepatitis B virus DNA were detectable for at least 12 days after cell plating. Whereas expression of duck hepatitis B pre-surface antigen was constant during this time, expression of duck hepatitis B core antigen and of viral DNA rapidly declined. This diminished production of viral components in vitro was paralleled by a change of the hepatocytes toward a fibroblast-like morphology. Supplementation of cell culture medium with 2% dimethyl sulfoxide, a solvent known to maintain the differentiated state of cultured cells, retained competence of the cultured hepatocytes to express duck hepatitis B core antigen and duck hepatitis B virus DNA at high levels. In a second set of experiments, duck hepatitis B virus negative hepatocytes were infected with duck hepatitis B virus from serum of congenitally infected ducks. Dimethyl sulfoxide remarkably improved the competence of cultured duck hepatocytes to become productively infected. This function was maintained for at least 12 days postplating.