The roles of growth factors and hormones in the regulation of muscle satellite cells for cultured meat production

The Role of Insulin in the Proliferation and Differentiation of Bovine Muscle Satellite (Stem) Cells for Cultured Meat Production

Muscle satellite (stem) cells (MSCs) reside in skeletal muscle and are essential for myogenesis. Thus, MSCs are widely used in cultured meat research. This study aimed to identify substances that promote MSC proliferation and differentiation while maintaining their intrinsic properties, with the long-term goal of replacing fetal bovine serum (FBS) for bovine MSC cultivation. Therefore, this study evaluated the effects of six growth factors (TGF-β, HGF, PDGF, insulin, IGF-1, and EGF) and the cytokine IL-2 on bovine MSCs. Each factor was applied during the proliferation and differentiation of MSCs, and the proliferation rate, differentiation rate, and expression of relevant mRNA and proteins were analyzed. Insulin most effectively promoted MSC proliferation and differentiation. Specifically, insulin increased cell proliferation rates, proliferation markers Ki67 and PCNA expressions, and markers of differentiation, such as myotube formation and creatine kinase activity, alongside the expressions of MYOD, MYOG, and MYH. Furthermore, insulin suppressed low FBS-induced reductions in proliferation and differentiation markers. This study suggests insulin can promote MSC proliferation and differentiation and reduce FBS usage. Thus, this study provides a potential means of cultivating MSCs on a large scale for cultured meat production.

Enhancing recombinant growth factor and serum protein production for cultivated meat manufacturing

The commercial growth factors (GFs) and serum proteins (SPs) contribute to the high cost associated with the serum-free media for cultivated meat production. Producing recombinant GFs and SPs in scale from microbial cell factories can reduce the cost of culture media. Escherichia coli is a frequently employed host in the expression recombinant GFs and SPs. This review explores critical strategies for cost reduction in GFs and SPs production, focusing on yield enhancement, product improvement, purification innovation, and process innovation. Firstly, the review discusses the use of fusion tags to increase the solubility and yield of GFs & SPs, highlighting various studies that have successfully employed these tags for yield enhancement. We then explore how tagging strategies can streamline and economize the purification process, further reducing production costs. Additionally, we address the challenge of low half-life in GFs and SPs and propose potential strategies that can enhance their stability. Furthermore, improvements in the E. coli chassis and cell engineering strategies are also described, with an emphasis on the key areas that can improve yield and identify areas for cost minimization. Finally, we discuss key bioprocessing areas which can facilitate easier scale-up, enhance yield, titer, and productivity, and ultimately lower long-term production costs. It is crucial to recognize that not all suggested approaches can be applied simultaneously, as their relevance varies with different GFs and SPs. However, integrating of multiple strategies is anticipated to yield a cumulative effect, significantly reducing production costs. This collective effort is expected to substantially decrease the price of cultivated meat, contributing to the broader goal of developing sustainable and affordable meat.

The Effects of Laxogenin and 5-Alpha-hydroxy-laxogenin on Myotube Formation and Maturation During Cultured Meat Production

Cultured meat (CM) is derived from the in vitro myogenesis of muscle satellite (stem) cells (MSCs) and offers a promising alternative protein source. However, the development of a cost-effective media formulation that promotes cell growth has yet to be achieved. In this study, laxogenin (LAX) and 5-alpha-hydroxy-laxogenin (5HLAX) were computationally screened against myostatin (MSTN), a negative regulator of muscle mass, because of their antioxidant properties and dual roles as MSTN inhibitors and enhancers of myogenesis regulatory factors. In silico analysis showed LXG and 5HLXG bound to MSTN with binding free energies of -7.90 and -8.50 kcal/mol, respectively. At a concentration of 10 nM, LAX and 5HLAX effectively inhibited the mRNA and protein expressions of MSTN, promoted myogenesis, and enhanced myotube formation and maturation. In addition, by acting as agonists of ROS downregulating factors, they exhibited antioxidative effects. This study shows that supplementation with LAX or 5HLAX at 10 nM in CM production improves texture, quality, and nutritional value. We believe this study fills a research gap on media development for myotube formation and maturation, which are important factors for large-scale in vitro CM production that improve product quality, nutritional value, and efficacy.

Establishment and characterization of the Cuvier's beaked whale (Ziphius cavirostris) myogenic cell line

In this study we present the first in vitro model based on a muscle-derived cell line from a male Cuvier's Beaked whale stranded along the Italian coastline. In the myogenic cell line at T0 stage we performed the growth rate assay, the karyotyping, the CBA chromosome banding, G banding, nucleolar organizer regions and telomere analysis and immunocytochemical analysis. The cell characterization at the T2 and T4 stage included: assessment of fusion index, the ultrastructural analysis and immunocytochemical analysis. The population doubling time was determined to be ∼54 h. The cell fusion index at the T2 stage was 8.2 +/- 5 %, at the T4 stage increased at index 28 +/- 10 %. The karyotype analysis revealed a 2n = 42, XY, two pairs of nucleolus organizer regions (NORs), characteristic CBA-banding and PNA-telomeric regions by FISH-mapping. The immunocytochemical results revealed that we generated a heterogeneous population of myogenic cells. A cell population express β-actin, myosin and vimentin and a sub-population of cells was desmin-positive. In details, at the T0 stage, both cell populations were undifferentiated mononucleated myoblast. At the T2 and T4 stage, the cells were capable of fusion in elongated multinucleated myotubes, probably resulting from the fusion of the myoblasts. This Cuvier's Beaked whale cell line, represents a new opportunity to better understand the physiological features of the cetacean Ziphius cavirostris myogenic cells. The possibility of setting up culture conditions that mimic the in vivo microenvironment, strengthen the importance of in vitro models for toxicological studies investigating water pollutants effects on cells.

Inhibition of myotube formation by platelet-derived growth factor subunit B in QM7 cells

OBJECTIVE

The primary objective of this study was to investigate the role and regulatory mechanisms of platelet-derived growth factor subunit B (PDGFB) in muscle differentiation.

METHODS

In this study, a vector for PDGFB was designed and transfected into quail muscle cells to investigate its role and regulatory mechanism during muscle formation. To investigate the inhibitory mechanisms of PDGFB on myogenic differentiation, the mRNA expression levels of various genes and the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK 1/2), both known to regulate muscle development and differentiation were compared.

RESULTS

PDGFB-overexpressed (OE) cells formed morphologically shorter and thinner myotubes and demonstrated a smaller total myotube area than did the control cells. This result was also confirmed at the molecular level by a reduced amount of myosin heavy chain protein in the PDGFB-OE cells. Therefore, PDGFB inhibits the differentiation of muscle cells. Additionally, the expression of myogenin (MYOG) significantly decreased in the PDGFBOE cells on days 2 and 4 compared with that in the control cells. The phosphorylation of ERK 1/2, an upstream protein that inhibits MYOG expression, increased in the PDGFB-OE cells on day 4 compared with that in the control cells. The decreased expression of MYOG in the PDGFB-OE cells increased by inhibition ERK 1/2 phosphorylation.

CONCLUSION

PDGFB may suppress myogenesis by reducing MYOG expression through ERK 1/2 phosphorylation. These findings can help understand muscle differentiation and potentially improve poultry meat production.

Exploring Sustainable Future Protein Sources

With the exponential growth of the world population and the decline in agricultural production due to global warming, it is predicted that there will be an inevitable shortage of food and meat resources in the future. The global meat consumption, which reached 328 million tons in 2021, is expected to increase by about 70% by 2050, and the existing livestock industry, which utilizes limited resources, is having difficulty meeting the demand. Accordingly, cultured meat produced by culturing cells in the laboratory, edible insects consumed after cooking or processing, and plant-based meat processed by extracting proteins from plants have been proposed as sustainable food alternatives. These future protein sources are gaining popularity among consumers who prefer a healthy diet due to their nutritional benefits, and they are receiving attention for their potential to reduce environmental impact. This review describes the types and characteristics of protein sources such as cultured meat, antiserum media, edible insects, soy protein, wheat protein, and other mushroom mycelia, processing processes and technologies, market status, institutional challenges and prospects, and mushroom cultured meat.

Skeletal muscle as a pro- and anti-inflammatory tissue: insights from children to adults and ultrasound findings

Previously regarded as a movement and posture control agent, the skeletal muscle is now recognized as an endocrine organ that may affect systemic inflammation and metabolic health. The discovery of myokines such as IL-6, released from skeletal muscle in response to physical exercise, is now one of the most recent insights. Myokines are the mediators of the balance between the pro-inflammatory and anti-inflammatory responses. This underscores the muscle function as a determinant of good health and prevention of diseases. Advances in ultrasound technology improved evaluation of muscle thickness, composition, and determining fat distribution. Combining imaging with molecular biology, researchers discovered the complicated interplay between muscle function, cytokine production and general health effects.The production of myokines with exercise showcasing the adaptability of muscles to high-stress conditions and contributing to metabolism and inflammation regulation. These findings have significant implications in order to provide improvement in metabolic and inflammatory diseases.

Causal roles of circulating cytokines in sarcopenia-related traits: a Mendelian randomization study

Background

Epidemiological and experimental evidence suggests that chronic inflammation plays an important role in the onset and progression of sarcopenia. However, there is inconsistent data on the inflammatory cytokines involved in the pathogenesis of sarcopenia. Therefore, we performed a two-sample Mendelian randomization (MR) analysis to explore the causal relationship between circulating cytokines and sarcopenia-related traits.

Methods

The MR analysis utilized genetic data from genome-wide association study that included genetic variations in 41 circulating cytokines and genetic variant data for appendicular lean mass (ALM), hand grip strength, and usual walking pace. Causal associations were primarily explored using the inverse variance-weighted (IVW) method, supplemented by MR-Egger, simple mode, weighted median, and weighted mode analyses. Additionally, sensitivity analyses were also performed to ensure the reliability and stability of the results.

Results

Three cytokines [hepatocyte growth factor (HGF), interferon gamma-induced protein 10 (IP-10), and macrophage colony-stimulating factor (M-CSF)] were positively associated with ALM (β: 0.0221, 95% confidence interval (CI): 0.0071, 0.0372, P= 0.0039 for HGF; β: 0.0096, 95%CI: 4e-04, 0.0189, P= 0.0419 for IP-10; and β: 0.0100, 95%CI: 0.0035, 0.0165, P= 0.0025 for M-CSF). Conversely, higher levels of interleukin-7 (IL-7), monocyte chemotactic protein 3 (MCP-3), and regulated on activation, normal T cell expressed and secreted (RANTES) were associated with decreased hand grip strength (β: -0.0071, 95%CI: -0.0127, -0.0014, P= 0.0140 for IL-7; β: -0.0064, 95%CI: -0.0123, -6e-04, P= 0.0313 for MCP-3; and β: -0.0082, 95%CI: -0.0164, -1e-04, P= 0.0480 for RANTES). Similarly, interleukin 1 receptor antagonist (IL-1RA) was negatively correlated with usual walking pace (β: -0.0104, 95%CI: -0.0195, -0.0013, P= 0.0254). Sensitivity analysis confirmed the robustness of these findings.

Conclusions

Our study provides additional insights into the pivotal role of specific inflammatory cytokines in the pathogenesis of sarcopenia. Further research is required to determine whether these cytokines can be used as targets for the prevention and treatment of sarcopenia.

Optimizing interleukin-6 and 8 expression, clarification and purification in plant cell packs and plants for application in advanced therapy medicinal products and cellular agriculture

Healthcare and nutrition are facing a paradigm shift in light of advanced therapy medicinal products (ATMPs) and cellular agriculture options respectively. Both options heavily rely on some sort of animal cell culture, e.g. autologous stem cells. These cultures require various growth factors, such as interleukin-6 and 8 (IL-6/8), in a pure, safe and sustainable form that can be provided in a scalable manner. Plants seem well suited for this task because purification of small proteins can be readily achieved by membrane separation, human/animal pathogens do not replicate in plants and production can be scaled up using in-door farming or agricultural practices. Here, we illustrate this capacity by first optimizing the codon usage of IL-6/8 for translation in Nicotiana spp., as well as testing the effect of untranslated regions and product targeting to different sub-cellular compartments on expression in a high-throughput plant cell pack (PCP) assay. In the chloroplast, IL-6 accumulated up to 6.9±3.8 (SD, n=2) and 14.4±7.4 mg kg-1 (SD, n=5) were observed in case of IL-8. When transferring IL-8 expression into whole plants, accumulation was 12.3±1.5 mg kg-1 (SD, n=3). After extraction and clarification, IL-8 was purified using a two-stage process consisting of an ultrafiltration/diafiltration step with 100 kDa and 10 kDa cut off membranes followed by an IMAC polishing step. The purity, yield and recovery were 97.8%, 6.6 mg kg-1 and 38%, respectively. We evaluated the ability of the proposed purification process to remove endotoxins to ensure the compatibility of plant-made growth factors with cell culture.

Microbiological and chemical hazards in cultured meat and methods for their detection

Cultured meat, which involves growing meat in a laboratory rather than breeding animals, offers potential benefits in terms of sustainability, health, and animal welfare compared to conventional meat production. However, the cultured meat production process involves several stages, each with potential hazards requiring careful monitoring and control. Microbial contamination risks exist in the initial cell collection from source animals and the surrounding environment. During cell proliferation, hazards may include chemical residues from media components such as antibiotics and growth factors, as well as microbial issues from improper bioreactor sterilization. In the differentiation stage where cells become muscle tissue, potential hazards include residues from scaffolding materials, microcarriers, and media components. Final maturation and harvesting stages risk environmental contamination from nonsterile conditions, equipment, or worker handling if proper aseptic conditions are not maintained. This review examines the key microbiological and chemical hazards that must be monitored and controlled during the manufacturing process for cultured meats. It describes some conventional and emerging novel techniques that could be applied for the detection of microbial and chemical hazards in cultured meat. The review also outlines the current evolving regulatory landscape around cultured meat and explains how thorough detection and characterization of microbiological and chemical hazards through advanced analytical techniques can provide crucial data to help develop robust, evidence-based food safety regulations specifically tailored for the cultured meat industry. Implementing new digital food safety methods is recommended for further research on the sensitive and effective detection of microbiological and chemical hazards in cultured meat.

Targeting myostatin using quercetin as a media supplement to improve myogenesis for cultured meat production: An in silico and in vitro study

Cultured meat (CM) is an alternative protein food and is produced by cultivating muscle satellite (stem) cells (MSCs) derived from livestock animals (bovine, chickens, and porcine) through myogenesis leading to generate muscle mass. Myostatin (MSTN) is well well-known negative regulator of myogenesis, and in the present study, in silico screening of natural compounds was performed to identify MSTN inhibitors. Interestingly, quercetin was found to inhibit MSTN (binding energy -7.40 kcal/mol), and this was further validated by a 100 ns molecular dynamics simulation. Quercetin was added to culture media to boost myogenesis, and its potent antioxidant property helped maintain media pH. Furthermore, quercetin increased the myotube thickness and length, increased MSC differentiation, and upregulated the gene and protein expressions of myoblast determination protein 1 (MYOD), Myogenin (MYOG), and Myosin heavy chains (MYH) in vitro. In addition, quercetin inhibited the activities of MSTN, activin receptor type-2B (ACVR2B), and SMAD2 and 3, and thus significantly enhanced MSC differentiation and myotube formation. Overall, this study shows that quercetin might be useful for enhancing large-scale CM production. It is hoped that this study provides a starting point for research in the CM area aimed to enhancing product quality, nutritional values, and the efficacy of large-scale production.

Current technology and industrialization status of cell-cultivated meat

Interest and investment in cultivated meat are increasing because of the realization that it can effectively supply sufficient food resources and reduce the use of livestock. Nevertheless, accurate information on the specific technologies used for cultivated meat production and the characteristics of cultivated meat is lacking. Authorization for the use of cultivated meat is already underway in the United States, Singapore, and Israel, and other major countries are also expected to approve cultivated meat as food once the details of the intricate process of producing cultivated meat, which encompasses stages such as cell proliferation, differentiation, maturation, and assembly, is thoroughly established. The development and standardization of mass production processes and safety evaluations must precede the industrialization and use of cultivated meat as food. However, the technology for the industrialization of cultivated meat is still in its nascent stage, and the mass production process has not yet been established. The mass production process of cultivated meat may not be easy to disclose because it is related to the interests of several companies or research teams. However, the overall research flow shows that equipment development for mass production and cell acquisition, proliferation, and differentiation, as well as for three-dimensional production supports and bioreactors have not yet been completed. Therefore, additional research on the mass production process and safety of cultivated meat is essential. The consumer's trust in the cultivated meat products and production technologies recently disclosed by some companies should also be analyzed and considered for guiding future developments in this industry. Furthermore, close monitoring by academia and the government will be necessary to identify fraud in the cultivated meat industry.

Fibroblast Growth Factor 21: A Fascinating Perspective on the Regulation of Muscle Metabolism

Fibroblast growth factor 21 (FGF21) plays a vital role in normal eukaryotic organism development and homeostatic metabolism under the influence of internal and external factors such as endogenous hormone changes and exogenous stimuli. Over the last few decades, comprehensive studies have revealed the key role of FGF21 in regulating many fundamental metabolic pathways, including the muscle stress response, insulin signaling transmission, and muscle development. By coordinating these metabolic pathways, FGF21 is thought to contribute to acclimating to a stressful environment and the subsequent recovery of cell and tissue homeostasis. With the emphasis on FGF21, we extensively reviewed the research findings on the production and regulation of FGF21 and its role in muscle metabolism. We also emphasize how the FGF21 metabolic networks mediate mitochondrial dysfunction, glycogen consumption, and myogenic development and investigate prospective directions for the functional exploitation of FGF21 and its downstream effectors, such as the mammalian target of rapamycin (mTOR).

Study on the current research trends and future agenda in animal products: an Asian perspective

This study aimed to analyze the leading research materials and research trends related to livestock food in Asia in recent years and propose future research agendas to ultimately contribute to the development of related livestock species. On analyzing more than 200 relevant articles, a high frequency of studies on livestock species and products with large breeding scales and vast markets was observed. Asia possesses the largest pig population and most extensive pork market, followed by that of beef, chicken, and milk; moreover, blood and egg markets have also been studied. Regarding research keywords, "meat quality" and "probiotics" were the most common, followed by "antioxidants", which have been extensively studied in the past, and "cultured meat", which has recently gained traction. The future research agenda for meat products is expected to be dominated by alternative livestock products, such as cultured and plant-derived meats; improved meat product functionality and safety; the environmental impacts of livestock farming; and animal welfare research. The future research agenda for dairy products is anticipated to include animal welfare, dairy production, probiotic-based development of high-quality functional dairy products, the development of alternative dairy products, and the advancement of lactose-free or personalized dairy products. However, determining the extent to which the various research articles' findings have been applied in real-world industry proved challenging, and research related to animal food laws and policies and consumer surveys was lacking. In addition, studies on alternatives for sustainable livestock development could not be identified. Therefore, future research may augment industrial application, and multidisciplinary research related to animal food laws and policies as well as eco-friendly livestock production should be strengthened.

Current technologies, regulation, and future perspective of animal product analogs - A review

The purpose of this study was to investigate the recent development of meat analog, industrialization, and the related legal changes worldwide. Summarizing the current status of the industrialization of meat analog, studies on plant-based meat, mycoprotein, and edible insects were mainly conducted to investigate their sensory properties (texture, taste, flavor, and color resembling meat), nutritional and safety evaluations, acquisition method of meat alternatives, and commercialization. Cultured meat is mainly studied for developing muscle satellite cell acquisition and support techniques or materials for the formation of structures. However, these technologies have not reached the level for active industrialization. Even though there are differences in the food categories and labeling between countries, it is common to cause confusion or to relay false information to consumers; therefore, it is important to provide accurate information. In this study, there were some differences in the food classification and food definition (labeling) contents for each country and state depending on the product shape or form, raw materials, and ingredients. Therefore, this study can provide information about the current research available on meat alternatives, improve regulation, and clarify laws related to the meat analog industry, which can potentially grow alongside the livestock industry.

The Effect of Long-Term Passage on Porcine SMCs' Function and the Improvement of TGF-β1 on Porcine SMCs' Secretory Function in Late Passage

Cultured meat is one of the meat substitutes produced through tissue engineering and other technologies. Large-scale cell culture is the key for cultured meat products to enter the market. Therefore, this study is aimed to explore the effect of long-term passage in vitro on smooth muscle cells (SMCs) and the effect of transforming growth factor-β1 (TGF-β1) on SMCs in the late passage. Multiple passages lead to the decline of the proliferation rate of SMCs in the proliferation stage and the differentiation ability in the differentiation stage. Transcriptome results showed that the ECM pathway and aging-related signaling pathways were significantly up-regulated in the late passage period. TGF-β1 did not promote SMCs of late passage proliferation at the proliferation stage but promoted the gene and protein expression of collagen as the main protein of the extracellular matrix proteins at the differentiation stage. In addition, proteomic analysis revealed that TGF-β1 promoted the expression of cell adhesion molecules which activate the Hippo signaling pathway and the HIF-1 signaling pathway and further promoted the production of collagen-containing extracellular matrix proteins. This could provide ideas for large-scale production of cultured meat products using SMCs.