Effect of serum replacement with plysate on cell growth and metabolismin primary cultures of human skeletal muscle

Platelet-Rich Plasma Promotes the Expansion of Human Myoblasts and Favors the In Vitro Generation of Human Muscle Reserve Cells in a Deeper State of Quiescence

Stem cell therapy holds significant potential for skeletal muscle repair, with in vitro-generated human muscle reserve cells (MuRCs) emerging as a source of quiescent myogenic stem cells that can be injected to enhance muscle regeneration. However, the clinical translation of such therapies is hampered by the need for fetal bovine serum (FBS) during the in vitro generation of human MuRCs. This study aimed to determine whether fresh allogeneic human platelet-rich plasma (PRP) combined or not with hyaluronic acid (PRP-HA) could effectively replace xenogeneic FBS for the ex vivo expansion and differentiation of human primary myoblasts. Cells were cultured in media supplemented with either PRP or PRP-HA and their proliferation rate, cytotoxicity and myogenic differentiation potential were compared with those cultured in media supplemented with FBS. The results showed similar proliferation rates among human myoblasts cultured in PRP, PRP-HA or FBS supplemented media, with no cytotoxic effects. Human myoblasts cultured in PRP or PRP-HA showed reduced fusion ability upon differentiation. Nevertheless, we also observed that human MuRCs generated from PRP or PRP-HA myogenic cultures, exhibited increased Pax7 expression and delayed re-entry into the cell cycle upon reactivation, indicating a deeper quiescent state of human MuRCs. These results suggest that allogeneic human PRP effectively replaces FBS for the ex vivo expansion and differentiation of human myoblasts and favors the in vitro generation of Pax7High human MuRCs, with important implications for the advancement of stem cell-based muscle repair strategies.

Palbociclib Induces Senescence in Melanoma and Breast Cancer Cells and Leads to Additive Growth Arrest in Combination With Irradiation

Introduction

Several kinase inhibitors (KI) bear the potential to act as radiosensitizers. Little is known of the radiosensitizing effects of a wide range of other KI like palbociclib, which is approved in ER+/HER2- metastatic breast cancer.

Method

In our study, we used healthy donor fibroblasts and breast cancer and skin cancer cells to investigate the influence of a concomitant KI + radiation therapy. Cell death and cell cycle distribution were studied by flow cytometry after Annexin-V/7-AAD and Hoechst staining. Cellular growth arrest was studied in colony-forming assays. Furthermore, we used C12-FDG staining (senescence) and mRNA expression analysis (qPCR) to clarify cellular mechanisms.

Results

The CDK4/6 inhibitor palbociclib induced a cell cycle arrest in the G0/G1 phase. Cellular toxicity (cell death) was only slightly increased by palbociclib and not enhanced by additional radiotherapy. As the main outcome of the colony formation assays, we found that cellular growth arrest was induced by palbociclib and improved by radiotherapy in an additive manner. Noticeably, palbociclib treatment clearly induced senescence not only in breast cancer and partly in melanoma cells, but also in healthy fibroblasts. According to these findings, the downregulation of senescence-related FOXM1 might be an involved mechanism of the senescence-induction potential of palbociclib.

Conclusion

The effect on cellular growth arrest of palbociclib and radiotherapy is additive. Palbociclib induces permanent G0/G1 cell cycle arrest by inducing senescence in fibroblasts, breast cancer, and melanoma cells. Direct cell death induction is only a minor secondary mechanism of action. Concomitant KI and radiotherapy is a strategy worth studying in clinical trials.

A Novel Fibroblast Reporter Cell Line for in vitro Studies of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease of the lower respiratory tract with restricted therapeutic options. Repetitive injury of the bronchoalveolar epithelium leads to activation of pulmonary fibroblasts, differentiation into myofibroblasts and excessive extracellular matrix (ECM) deposition resulting in aberrant wound repair. However, detailed molecular and cellular mechanisms underlying initiation and progression of fibrotic changes are still elusive. Here, we report the generation of a representative fibroblast reporter cell line (10-4A BFP ) to study pathophysiological mechanisms of IPF in high throughput or high resolution in vitro live cell assays. To this end, we immortalized primary fibroblasts isolated from the distal lung of Sprague-Dawley rats. Molecular and transcriptomic characterization identified clone 10-4A as a matrix fibroblast subpopulation. Mechanical or chemical stimulation induced a reversible fibrotic state comparable to effects observed in primary isolated fibroblasts. Finally, we generated a reporter cell line (10-4A BFP ) to express nuclear blue fluorescent protein (BFP) under the promotor of the myofibroblast marker alpha smooth muscle actin (Acta2) using CRISPR/Cas9 technology. We evaluated the suitability of 10-4A BFP as reporter tool in plate reader assays. In summary, the 10-4A BFP cell line provides a novel tool to study fibrotic processes in vitro to gain new insights into the cellular and molecular processes involved in fibrosis formation and propagation.

Human platelet lysate efficiency, stability, and optimal heparin concentration required in culture of mammalian cells

Background

Fetal bovine serum (FBS) has been used to support the growth and proliferation of mammalian cells for decades. Owing to several risk factors associated with FBS, several trials have been conducted to evaluate substitutes to FBS with the same efficiency and the lower risk issues.

Methods

In this study, human platelet lysate (HPL) derived from activated human platelets was evaluated as an alternative to FBS due to the associated risk factors. To evaluate the efficiency of the preparation process, platelet count was performed before and after activation. The concentrations of several growth factors and proteins were measured to investigate HPL efficiency. HPL stability was studied at regular intervals, and optimal heparin concentration required to prevent gel formation in various media was determined. The biological activity of HPL and FBS was compared by evaluating the growth performance of Vero and Hep-2 cell lines.

Results

Result of platelet count assay revealed the efficiency of HPL preparation process. Growth factor concentrations in HPL were significantly higher than those in FBS, while the protein content of HPL was lower than that of FBS. Stability study data showed that the prepared HPL was stable for up to 15 months at -20℃. Ideal heparin concentration to be used in different media was dependent on calcium concentration. Results of cell viability assay showed that HPL was superior to FBS in supporting the growth and proliferation of Vero and Hep-2 cells.

Conclusion

The HPL prepared by the mechanical activation of platelets may serve as an efficient alternative to FBS in cell culture process.

Remote Ischemic Preconditioning induces Cardioprotective Autophagy and Signals through the IL-6-Dependent JAK-STAT Pathway

Autophagy is a cellular process by which mammalian cells degrade and assist in recycling damaged organelles and proteins. This study aimed to ascertain the role of autophagy in remote ischemic preconditioning (RIPC)-induced cardioprotection. Sprague Dawley rats were subjected to RIPC at the hindlimb followed by a 30-min transient blockade of the left coronary artery to simulate ischemia reperfusion (I/R) injury. Hindlimb muscle and the heart were excised 24 h post reperfusion. RIPC prior to I/R upregulated autophagy in the rat heart at 24 h post reperfusion. In vitro, autophagy inhibition or stimulation prior to RIPC, respectively, either ameliorated or stimulated the cardioprotective effect, measured as improved cell viability to mimic the preconditioning effect. Recombinant interleukin-6 (IL-6) treatment prior to I/R increased in vitro autophagy in a dose-dependent manner, activating the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway without affecting the other kinase pathways, such as p38 mitogen-activated protein kinases (MAPK), and glycogen synthase kinase 3 Beta (GSK-3β) pathways. Prior to I/R, in vitro inhibition of the JAK-STAT pathway reduced autophagy upregulation despite recombinant IL-6 pre-treatment. Autophagy is an essential component of RIPC-induced cardioprotection that may upregulate autophagy through an IL-6/JAK-STAT-dependent mechanism, thus identifying a potentially new therapeutic option for the treatment of ischemic heart disease.

Serum-reduced media impacts on cell viability and protein expression in human lung epithelial cells

Serum starvation is a widely used condition in molecular biology experiments. Opti‐MEM is a serum‐reduced media used during transfection of genetic molecules into mammalian cells. However, the impact of such media on cell viability and protein synthesis is unknown. A549 human lung epithelial cell viability and morphology were adversely affected by growing in Opti‐MEM. The cellular protein levels of chloride intracellular channel protein 1, proteasome subunit alpha Type 2, and heat shock 70 kDa protein 5 were dysregulated in A549 cells after growing in serum‐reduced media. Small interfering RNA transfection was done in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum, and knockdown efficacy was determined compared with Opti‐MEM. Similar amounts of knockdown of the target proteins were achieved in DMEM, and cell viability was higher compared with Opti‐MEM after transfection. Careful consideration of the impact of Opti‐MEM media during the culture or transfection is important for experimental design and results interpretation.

Human serum and platelet lysate are appropriate xeno-free alternatives for clinical-grade production of human MuStem cell batches

BACKGROUND

Canine MuStem cells have demonstrated regenerative efficacy in a dog model of muscular dystrophy, and the recent characterization of human counterparts (hMuStem) has highlighted the therapeutic potential of this muscle-derived stem cell population. To date, these cells have only been generated in research-grade conditions. However, evaluation of the clinical efficacy of any such therapy will require the production of hMuStem cells in compliance with good manufacturing practices (GMPs). Because the current use of fetal bovine serum (FBS) to isolate and expand hMuStem cells raises several ethical, safety, and supply concerns, we assessed the use of two alternative xeno-free blood derivatives: human serum (HS) and a human platelet lysate (hPL).

METHODS

hMuStem cells were isolated and expanded in vitro in either HS-supplemented or hPL-supplemented media and the proliferation rate, clonogenicity, myogenic commitment potential, and oligopotency compared with that observed in FBS-supplemented medium. Flow cytometry and high-throughput 3'-digital gene expression RNA sequencing were used to characterize the phenotype and global gene expression pattern of hMuStem cells cultured with HS or hPL.

RESULTS

HS-supplemented and hPL-supplemented media both supported the isolation and long-term proliferation of hMuStem cells. Compared with FBS-based medium, both supplements enhanced clonogenicity and allowed for a reduction in growth factor supplementation. Neither supplement altered the cell lineage pattern of hMuStem cells. In vitro differentiation assays revealed a decrease in myogenic commitment and in the fusion ability of hMuStem cells when cultured with hPL. In return, this reduction of myogenic potential in hPL-supplemented cultures was rapidly reversed by substitution of hPL with HS or fibrinogen-depleted hPL. Moreover, culture of hMuStem cells in hPL hydrogel and fibrinogen-depleted hPL demonstrated that myogenic differentiation potential is maintained in heparin-free hPL derivatives.

CONCLUSIONS

Our findings indicate that HS and hPL are efficient and viable alternatives to FBS for the preparation of hMuStem cell batches in compliance with GMPs.

Serum albumin as a local therapeutic agent in cell therapy and tissue engineering

Albumin is a major plasma protein that has become ubiquitous in regenerative medicine research. As such, many studies have examined its structure and advantageous properties. However, a systematic and comprehensive understanding of albumin's role, capabilities and therapeutic potential still eludes the field. In the present work, we review how albumin is applied in tissue engineering, including cell culture and storage, in vitro fertilization and transplantation. Furthermore, we discuss how albumin's physiological role extends beyond a carrier for metal ions, fatty acids, pharmacons and growth factors. Albumin acts as a bacteriostatic coating that simultaneously promotes attachment and proliferation of eukaryotic cells. These properties with the combination of free radical scavenging, neutrophil activation and as a buffer molecule already make the albumin protein beneficial in healing processes supporting functional tissue remodeling. Nevertheless, recent data revealed that albumin can be synthesized by osteoblasts and its local concentration is raised after bone trauma. Interestingly, by increasing the local albumin concentration in vivo, faster bone healing is achieved, possibly because albumin recruits endogenous stem cells and promotes the growth of new bone. These data also suggest an active role of albumin, even though a specific receptor has not yet been identified. Together, this discussion sheds light on why the extravascular use of the albumin molecule is in the scope of scientific investigations and why it should be considered as a local therapeutic agent in regenerative medicine. © 2016 BioFactors, 43(3):315-330, 2017.

Glutathione-mediated effects of lithium in decreasing protein oxidation induced by mitochondrial complex I dysfunction

The aim of this study was to elucidate whether glutathione is involved in lithium's ability to decrease carbonylation and nitration produced by complex I inhibition, which is consistently found in BD. Neuroblastoma cells were treated with rotenone, a complex I inhibitor. Our results suggest that glutathione is essential for lithium's ability to ameliorate rotenone-induced protein carbonylation, but not nitration.

Serum starvation: caveat emptor

Serum starvation is one of the most frequently performed procedures in molecular biology and there are literally thousands of research papers reporting its use. In fact, this method has become so ingrained in certain areas of research that reports often simply state that cells were serum starved without providing any factual details as to how the procedure was carried out. Even so, we quite obviously lack unequivocal terminology, standard protocols, and perhaps most surprisingly, a common conceptual basis when performing serum starvation. Such inconsistencies not only hinder interstudy comparability but can lead to opposing and inconsistent experimental results. Although it is frequently assumed that serum starvation reduces basal activity of cells, available experimental data do not entirely support this notion. To address this important issue, we studied primary human myotubes, rat L6 myotubes and human embryonic kidney (HEK)293 cells under different serum starvation conditions and followed time-dependent changes in important signaling pathways such as the extracellular signal-regulated kinase 1/2, the AMP-activated protein kinase, and the mammalian target of rapamycin. Serum starvation induced a swift and dynamic response, which displayed obvious qualitative and quantitative differences across different cell types and experimental conditions despite certain unifying features. There was no uniform reduction in basal signaling activity. Serum starvation clearly represents a major event that triggers a plethora of divergent responses and has therefore great potential to interfere with the experimental results and affect subsequent conclusions.

"Humanized" stem cell culture techniques: the animal serum controversy

Cellular therapy is reaching a pinnacle with an understanding of the potential of human mesenchymal stem cells (hMSCs) to regenerate damaged tissue in the body. The limited numbers of these hMSCs in currently identified sources, like bone marrow, adipose tissue, and so forth, bring forth the need for their in vitro culture/expansion. However, the extensive usage of supplements containing xenogeneic components in the expansion-media might pose a risk to the post-transplantation safety of patients. This warrants the necessity to identify and develop chemically defined or “humanized” supplements which would make in vitro cultured/processed cells relatively safer for transplantation in regenerative medicine. In this paper, we outline the various caveats associated with conventionally used supplements of xenogenic origin and also portray the possible alternatives/additives which could one day herald the dawn of a new era in the translation of in vitro cultured cells to therapeutic interventions.

Alternative sources of adult stem cells: human amniotic membrane

Human amniotic membrane is a highly promising cell source for tissue engineering. The cells thereof, human amniotic epithelial cells (hAEC) and human amniotic mesenchymal stromal cells (hAMSC), may be immunoprivileged, they represent an early developmental status, and their application is ethically uncontroversial. Cell banking strategies may use freshly isolated cells or involve in vitro expansion to increase cell numbers. Therefore, we have thoroughly characterized the effect of in vitro cultivation on both phenotype and differentiation potential of hAEC. Moreover, we present different strategies to improve expansion including replacement of animal-derived supplements by human platelet products or the introduction of the catalytic subunit of human telomerase to extend the in vitro lifespan of amniotic cells. Characterization of the resulting cultures includes phenotype, growth characteristics, and differentiation potential, as well as immunogenic and immunomodulatory properties.