Effects of different cryoprotectants on the viability and biological characteristics of porcine preadipocyte

Comparison between concentration and type of intracellular cryoprotectants and the presence of sucrose for cryobanks of somatic cells derived from captive Pumas

The loss of wild biodiversity has prompted the development of cryobanks, such as those of somatic cells. This is the reality of Pumas, wild felids of ecological importance that suffer from anthropogenic actions, population decline, and subsequent loss of genetic diversity. Somatic cell banks are a strategy for conserving population diversity. We compared different concentrations and types of intracellular cryoprotectants (dimethyl sulfoxide, DMSO; ethylene glycol, EG) associated with 0.2 M of sucrose (SUC) in the cryopreservation of the somatic cells of captive Pumas. The cells were cryopreserved by slow freezing with different solutions containing Dulbecco's modified Eagle's medium with 10% fetal bovine serum and varying concentrations of DMSO and EG in the absence or presence of SUC. The cells were analyzed for morphological characteristics, viability, proliferative activity, metabolic activity, and apoptosis levels. Cells maintained similar fusiform morphology before and after cryopreservation. There was no difference in viability, regardless of the reduction in the concentration and type of intracellular cryoprotectants and sucrose. Similarly, proliferative activity, metabolic activity, and apoptosis levels were not altered by the composition of the cryoprotectants. In summary, we demonstrate that reducing the concentration of DMSO or EG ensures adequate cryopreservation of Puma somatic cells, regardless of the presence of SUC.

Cryopreservation and Revival of Human Mesenchymal Stromal Cells

Cell-based therapy is a promising and innovative new treatment for different degenerative and autoimmune diseases, and mesenchymal stromal cells (MSCs) from the bone marrow have demonstrated great therapeutic potential due to their immunosuppressive and regenerative capacities.The establishment of methods for large-scale expansion of clinical-grade MSCs in vitro has paved the way for their therapeutic use in clinical trials. However, the clinical application of MSCs also requires cryopreservation and banking of the cell products. To preserve autologous or allogeneic MSCs for future clinical applications, a reliable and effective cryopreservation method is required.Developing a successful cryopreservation protocol for clinical stem cell products, cryopreservation media, cryoprotectant agents (CPAs), the freezing container, the freezing temperature, and the cooling and warming rate are all aspects which should be considered.A major challenge is the selection of a suitable cryoprotectant which is able to penetrate the cells and yet has low toxicity.This chapter focuses on recent technological developments relevant for the cryopreservation of MSCs using the most commonly used cryopreservation medium containing DMSO and animal serum or human-derived products for research use and the animal protein-free cryopreservation media CryoStor (BioLife Solutions) for clinical use.

Expression Profiles and Biological Roles of miR-196a in Swine

MicroRNAs (miRNAs) are a class of small non-coding RNA molecules, which play important roles in animals by targeting mRNA transcripts for translational repression. Recent studies have demonstrated that miRNAs are involved in regulation of adipocyte development. The expression of miR-196a in different porcine tissues and developing fat tissues was detected, and gene ontology (GO) term enrichment was then used to predict the expression profiles and potential biological roles of miR-196a in swine. To further verify the roles of miR-196a in porcine adipocyte development, a recombinant adenovirus encoding miR-196a gene (Ad-miR-196a) was constructed and used to study the effect of miR-196a on preadipocyte proliferation and differentiation. Here, our data demonstrate that miR-196a displays a tissue-specific expression pattern and has comprehensive biological roles in swine, especially in adipose development. In addition, overexpression of miR-196a had no effect on preadipocyte proliferation, but induced preadipocyte differentiation by increasing expression of adipocyte specific markers, lipid accumulation and triglyceride content. These data represent the first demonstration of miR-196a expression profiles and roles in swine, thereby providing valuable insight into the functions of miR-196a in adipocyte biology.

The anti-adipogenic effect of PGRN on porcine preadipocytes involves ERK1,2 mediated PPARγ phosphorylation

Recent researches indicate that PGRN is closely related to diabetes and is regarded as a novel adipokine associated with obesity development, affecting adipocyte biology. In the present study, we investigated the effects and mechanisms of PGRN on porcine preadipocytes differentiation. Porcine preadipocytes were induced to differentiation with the addition of lentivirius-expressed PGRN shRNA at the early or late stage of induction period, and in the presence or absence of recombinant PGRN protein. The effects of PGRN on adipogenic genes expression and ERK activation were investigated. At the early stage of induction, knockdown of PGRN promoted differentiation, evidenced by enhanced lipid accumulation, upregulation of adipocyte markers, as well as master adipogenic transcription factors, PPARγ and C/EBPα. While, decreasing PGRN expression at the late stage of induction (day 3) had no effect on differentiation. These results suggested that PGRN functions in the early adipogenic events. Conversely, porcine preadipocytes differentiation was impaired by MDI and recombinant PGRN protein induction, the expressions of adipocyte markers were decreased. Further studies revealed that PGRN can specifically facilitate ERK1,2 activation, and this activation can be abolished by U0126. Moreover, PPARγ phosphorylation at serine 112 site was increased by PGRN treatment, which could reduce the transcriptional activity of PPARγ. We conclude that PGRN inhibits adipogenesis in porcine preadipocytes partially through ERK activation mediated PPARγ phosphorylation.

On-chip characterization of cryoprotective agent mixtures using an EWOD-based digital microfluidic device

For tissue engineering and regenerative medicine, cryopreservation, a technique for preserving biomaterials in the frozen state with cryoprotective agents (CPAs), is critically important for preserving engineered tissues (ETs) as well as cells necessary to create ETs. As more diverse ETs are produced using various cell types, CPAs and corresponding freeze/thaw (F/T) protocols need to be developed cell/tissue-type specifically. This is because CPAs and F/T protocols that have been successful for one cell/tissue type have proven to be difficult to adapt to other cell/tissue types. The most critical barrier to address this challenge is the inability to screen and identify CPA or CPA mixtures efficiently. In this paper, we developed an "electro-wetting-on-dielectic" (EWOD) based digital microfluidic platform to characterize and screen CPA mixtures cell-type specifically. The feasibility of the EWOD platform was demonstrated by characterizing and optimizing a mixture of dimethlysulfoxide (DMSO) and PBS for human breast cancer cell line as model CPA mixture and cell line. The developed platform multiplexed droplets of DMSO and PBS to create an array of DMSO-PBS mixtures, and mapped the phase change diagram of the mixture. After loading cell suspensions on the platform, the mixture was further screened on-chip for toxicity and cryoprotection. The results were discussed to illustrate the capabilities and limitations of the EWOD platform for cell and tissue-type specific optimization of CPA mixtures and F/T protocols.

Cytotoxicity effects of cryoprotectants as single-component and cocktail vitrification solutions

Cryoprotectant (CPA) cytotoxicity constitutes a challenge in developing cryopreservation protocols, specifically in vitrification where high CPA concentrations are necessary to achieve the ice-free, vitreous state. Few cytotoxicity studies have investigated vitrification-relevant concentrations of CPAs, and the benefits and disadvantages of cocktail solutions and of incorporating non-permeating solutes have not been fully evaluated. In this study, we address these issues by determining the cytotoxicity kinetics for dimethylsulfoxide (Me(2)SO) and 1,2-propanediol (PD) on alginate-encapsulated βTC-tet mouse insulinomas for a range of concentrations and temperatures. Cytotoxicity kinetics were also determined for two cocktails, DPS (3M Me(2)SO+3M PD+0.5M sucrose) and PEG400 (1M Me(2)SO+5M PD+0.34M poly(ethylene)glycol with M.W. of 400). PD was found to be more cytotoxic than Me(2)SO at higher concentrations and temperatures. This was reflected in PEG400 being more cytotoxic at room temperature than PEG400 at 4°C or DPS at either temperature. Addition of non-permeating solutes increased the cytotoxicity of cocktails. Furthermore, results indicate that CPA cytotoxicity may not be additive and that combining CPAs may increase cytotoxicity synergistically. Finally, when comparing cytotoxic effects towards encapsulated HepG2 and βTC-tet cells, and towards βTC-tet cells in capsules and in monolayers, CPAs appear more cytotoxic towards cells with higher metabolic activity. The incorporation of these results in the rational design of CPA addition/removal processes in vitrification is discussed.

Cryopreservation and revival of mesenchymal stromal cells

Over the past few years, the pace of preclinical stem cell research is astonishing and adult stem cells have become the subject of intense research. Due to the presence of promising supporting preclinical data, human clinical trials for stem cell regenerative treatment of various diseases have been initiated. As there has been a precedent for the use of bone marrow stem cells in the treatment of hematological malignancies and ischemic heart diseases through randomized clinical safety and efficacy trials, the development of new therapies based on culture-expanded human mesenchymal stromal cells (MSCs) opens up new possibilities for cell therapy. To facilitate these applications, cryopreservation and long-term storage of MSCs becomes an absolute necessity. As a result, optimization of this cryopreservation protocol is absolutely critical. The major challenge during cellular cryopreservation is the lethality associated with the cooling and thawing processes. The major objective is to minimize damage to cells during low temperature freezing and storage and the use of a suitable cryoprotectant. The detrimental effects of cellular cryopreservation can be minimized by controlling the cooling rate, using better cryoprotective agents, maintaining appropriate storage temperatures, and controlling the cell thawing rate. As is described in this chapter, human MSCs can either be frozen in cryovials or in freezing bags together with cryopreserve solutions containing dimethyl sulfoxide (DMSO).

SOCS3 inhibits insulin signaling in porcine primary adipocytes

Insulin resistance is a major player in the pathogenesis of type II diabetes, the metabolic syndrome, and obesity. SOCS3 plays an important role in the development of insulin resistance. To investigate the role of SOCS3 in porcine adipocyte insulin signaling, we first detected the effect of insulin on SOCS3 mRNA and protein expression in porcine primary adipocytes by real-time RT-PCR and Western blotting. Then, we constructed a recombinant adenovirus encoding SOCS3 gene (Ad-SOCS3) which was used to infect differentiated porcine primary adipocytes for 3 days. The expression and phosphorylation of main insulin signaling components were detected by Western blotting. The results showed that 100 nM insulin could induce SOCS3 mRNA expression but not protein expression, and overexpression of SOCS3 decreased IRS1 protein level, insulin-stimulated IRS1 tyrosine phosphorylation, PI3K activation, and Akt phosphorylation, but increased IRS1 serine phosphorylation in porcine primary adipocytes. These results indicate that SOCS3 is an important negative regulator of insulin signaling in porcine adipocytes. Thus, SOCS3 may be a novel therapeutic target for the prevention or treatment of insulin resistance and type II diabetes.

Evaluation of polyvinylpyrrolidone as a cryoprotectant for adipose tissue-derived adult stem cells

The objective of this study was to test the hypothesis that human adipose tissue-derived adult stem cells (ASCs) can be effectively cryopreserved and stored in liquid nitrogen using a freezing medium containing a high-molecular-weight polymer, polyvinylpyrrolidone (PVP), as the cryoprotective agent (CPA) instead of dimethylsulfoxide (DMSO). To this end we investigated the postfreeze/thaw viability and apoptotic behavior of passage 1 ASCs cryopreserved in 15 different media: (i) the traditional media containing Dulbecco's modified Eagle's medium (DMEM) with 80% fetal calf serum (FCS) and 10% DMSO; (ii) DMEM with 80% human serum (HS) and 10% DMSO; (iii) DMEM with various concentrations (1%, 5%, 10%, 20%, and 40%) of PVP as the sole CPA; (iv) DMEM with PVP (5%, 10%, and 20%) and HS (10%); (v) DMEM with PVP (5%, 10%, and 20%) and FCS (10%); and (vi) DMEM with PVP (10%) and FCS (40% and 80%). Approximately 1 mL (10(6) cells/mL) of passage 1 ASCs were frozen overnight in a -80 degrees C freezer and stored in liquid nitrogen for 2 weeks before being rapidly thawed in a 37 degrees C water bath (1-2 min of agitation), resuspended in culture media, and seeded in separate wells of a six-well plate for a 24-h incubation period at 37 degrees C. After 24 h, the thawed samples were analyzed by bright-field microscopy and flow cytometry. The results suggest that the absence of DMSO significantly increases the fraction of apoptotic and/or necrotic ASCs. However, the percentage of viable cells obtained with 10% PVP and DMEM was comparable with that obtained in freezing media with DMSO and serum (HS or FCS), that is, approximately 70% + or - 8% and approximately 83% + or - 8%, respectively. Slightly enhanced cell viability was observed with the addition of serum (either HS or FCS) to the freezing media containing PVP as the CPA. Adipogenic and osteogenic differentiation behaviors of the frozen thawed cells were also assessed using histochemical staining and optical density measurements and the expression of adipogenic-associated genes was analyzed using reverse transcription-polymerase chain reaction. Our results suggest that after thawing, ASC viability and adipogenic and osteogenic differentiation abilities can be maintained even when ASCs are frozen in the absence of serum but with 10% PVP in DMEM.

Regulation of ATGL expression mediated by leptin in vitro in porcine adipocyte lipolysis

Adipose triglyceride lipase (ATGL), as an adipose-enriched protein, is able to hydrolyze triglycerides and plays an important part in triglyceride lipolysis of fat tissue. Leptin, an adipocyte cytokine, can increase the fat decomposition process. Many phenomena indicate that ATGL has a close relationship with leptin's promoting the hydrolysis of triglycerides. However, the regulatory mechanism of ATGL in leptin's promoting fat hydrolysis has not been directly and systematically studied yet. This study demonstrated that ATGL was expressed in vitro by leptin regulation. The amount of ATGL mRNA increased and the amount of ATGL protein decreased based on a dose-dependent manner when leptin concentrations ranged from 5 to 50 ng/ml were used to treat fully differentiated porcine adipocytes for 3 h. In addition, this study revealed that JAK-STAT and MAPK signaling pathways, as well as PPAR gamma all played important roles in the ATGL expression mediated by leptin.

Expression of TGH and its role in porcine primary adipocyte lipolysis

AIMS

Triacylglycerol hydrolase (TGH) plays an important role in intracellular lipid metabolism. However, most previous studies on TGH were focused on rodent animals. Pig is considered as one of the best models for studying obesity, diabetes, and other lipid metabolism related diseases. So far, we do not know whether TGH is to play a role in lipolysis in porcine primary adipocyte through stimulation by hormones as Hormone-sensitive lipase (HSL). The objective of this study is to explore the mechanisms that regulate TGH expression in porcine adipocyte and its role in fasting-induced and Isoproterenol-stimulated lipolysis in porcine primary adipocytes.

MATERIALS AND METHODS

Stromal-vascular cells containing preadipocytes were isolated from cervical and dorsal subcutaneous adipose tissues of approximately 3-day-old Chinese male piglets. After confluence, the differentiation was induced by Insulin, hydrocortisone, and transferrin. The primary adipocytes were cultured in various concentration (0.1 to 200 micromol/l) Isoproterenol for 0-12 h or serum-free medium after differentiation. The glycerol release and triacylglycerol (TG) contents were detected when the cells were collected. Then, expression of TGH and HSL mRNA and their protein were determined by RT-PCR, Western Blot, and lipolytic analysis.

RESULTS

Both TGH mRNA and protein were not detected on day 0, but as differentiation was induced, their expression displayed a great increase. The expression of TGH mRNA showed the highest level on day 4, but its protein reached the highest level on day 6 and began to fall down from day 8. The expression of TGH mRNA and proteins was increased in serum-free media, and mRNA expression was decreased while changed into complete media again. The glycerol release increased significantly when the cells were cultured with serum-free media. The lower concentration of Isoproterenol (0.1 and 1 micromol/l) did not affect the expression of TGH and HSL, but higher concentration (10, 100, and 200 micromol/l) could greatly up-regulate HSL expression but did not affect TGH level. Also, the higher concentration of Isoproterenol could increase the glycerol release and decrease TG content in dose-dependent manner.

CONCLUSIONS

These results suggested that TGH expression is differentiation-dependent in porcine primary adipocytes and TGH plays a role in fasting-induced lipolysis not hormone-stimulated lipolysis.

Preserved proliferative capacity and multipotency of human adipose-derived stem cells after long-term cryopreservation

BACKGROUND

Human adipose-derived stem (stromal) cells are promising as a regenerative therapy tool for defective tissues of mesenchymal lineage, including fat, bone, and cartilage, and blood vessels. In potential future clinical applications, adipose-derived stem cell cryopreservation could be an indispensable fundamental technology, as has occurred in other fields involving cell-based therapies using hematopoietic stem cells and umbilical cord blood cells.

METHODS

The authors examined the proliferative capacity and multipotency of human adipose-derived stem cells isolated from lipoaspirates of 18 patients in total before and after a 6-month cryopreservation following their defined protocol. Proliferative capacity was quantified by measuring doubling time in cell culture, and multipotency was examined with differentiation assays for chondrogenic, osteogenic, and adipogenic lineages. In addition, expression profiles of cell surface markers were determined by flow cytometry and compared between fresh and cryopreserved adipose-derived stem cells.

RESULTS

Cryopreserved adipose-derived stem cells fully retained the potential for differentiation into adipocytes, osteoblasts, and chondrocytes and for proliferative capacity. Flow cytometric analyses revealed that surface marker expression profiles remained constant before and after storage.

CONCLUSIONS

Adipose-derived stem cells can be cryopreserved at least for up to 6 months under the present protocol without any loss of proliferative or differentiation potential. These results ensure the availability of autologous banked adipose-derived stem cells for clinical applications in the future.

Tissue expression of porcine FoxO1 and its negative regulation during primary preadipocyte differentiation

The Forkhead transcription factor O 1 (FoxO1) gene plays an important role in the integration of hormone-activated signaling pathways with the complex transcriptional cascade that promotes clonal cell line differentiation. However, tissue expression of porcine FoxO1 and its function during porcine preadipocyte differentiation remained poorly understood. In the present study, we investigated tissue expressions of FoxO1 in pig by real time quantitative RT-PCR (qRT-PCR) and western blotting, and explored its role in porcine preadipocytes differentiation by RNA interference technique and qRT-PCR. FoxO1 gene expressions were highly in subcutaneous adipose and visceral adipose tissues, and higher in piglets than those in adults (P < 0.05). We showed that expression of endogenous FoxO1 in preadipocytes transfected with pBS/U6-siFoxO1-1748 expression vector was inhibited efficiently. After reducing expression of FoxO1, glycerol-3-phosphate dehydrogenase (GPDH) activity and triglyceride (TG) content increased from day 1 to 9, and the time-course expressions of several key adipogenic genes mRNA, including peroxisome proliferator-activated receptor gamma on day 3, 5, and 7, adipocyte fatty acid binding protein on day 1, 3, and 5, and sirtuin1 on day 1, 3, and 5, were increased significantly (P < 0.05). Lipoprotein lipase was unrelevant to FoxO1. By using insulin-like growth factor-I treating, expression of FoxO1 reduced at day 3 and 5 (P < 0.05), and significant differentiation of porcine preadipocyte with increasing number of filled-lipid cell and size of lipid droplets, GPDH activity and TG content were promoted. These results suggested that porcine FoxO1 gene took part in the regulation of adipose and was a negative transcription regulation factor in preadipocyte differentiation.

Alteration of mitochondrial oxidative capacity during porcine preadipocyte differentiation and in response to leptin

Mitochondrial apparatus is a fundamental aspect in cell, serving for amino acid biosynthesis, fatty acid oxidation (FAO), and ATP production. In this article, we investigated the change of mitochondrial oxidative capacity during porcine adipocyte differentiation and in response to leptin. Rhodamine 123 staining analysis showed about 2-fold increase of mitochondrial membrane electric potential in differentiated adipocyte in comparison with preadipocyte. The mRNA expression of Cytochromes c (Cyt c), carnitine palmitoyltransferase 1 (CPT1), and malate dehydrogenases (MDH) increased markedly (P < 0.05), but that of UCP2 decreased (P < 0.05). Moreover PGC-1alpha and UCP3 was very low and showed no changes during the adipocyte differentiation. The protein expression of Cyt c and the enzyme activity of Cytochrome c oxidase (COX) increased with preadipocyte differentiation, but cellular ATP level decreased. Furthermore, at the level of 10 and 100 ng/ml leptin not only selectively increased the gene expression of PGC-1alpha, CPT1, Cyt c, UCP2, and UCP3 (P < 0.05), but also enhanced COX enzyme activity which related to mitochondrial FAO. There is no change of Mitochondrial membrane electric potential and ATP level in cell treated by leptin. These results suggested Mitochondrial is not only critical in FAO, but also play an important role in adipogenesis.