A simple and robust serum-free media for the proliferation of muscle cells

Exosomal delivery of rapamycin modulates blood-brain barrier penetration and VEGF axis in glioblastoma

Exosomes (Exos), nanosized membranous vesicles (30-160 nm), have been validated as an effective drug delivery system capable of traversing biological barriers. Mesenchymal stem cells (MSCs), due to their near-limitless self-renewal capabilities, provide a plentiful source of exosomes for clinical applications. In this study, we utilized an exosome-encapsulated rapamycin (Exo-Rapa) delivery strategy, which permits the use of smaller drug dosages to achieve effects typically seen with higher dosages, thus enhancing drug efficacy. Moreover, Exos can transport pharmaceuticals across the blood-brain barrier (BBB) to the brain, and further penetrate GL261 cells to exert their effects. Within the tumor microenvironment, Exo-Rapa is released more rapidly and efficiently at the tumor site. The acidic conditions in tumors accelerate the release of Exo-Rapa, a characteristic that may make it a promising targeted therapeutic in future cancer research. Additionally, a series of in vivo experiments have further demonstrated the permeability of Exo-Rapa across the BBB, enabling it to accumulate at tumor sites; it also ameliorates inflammatory responses in Glioblastoma multiforme (GBM) mouse models and enhances anti-tumor activity through the regulation of angiogenesis via the VEGF/VEGFRs axis. Our results indicate that MSC-derived exosomes are a potent therapeutic carrier for GBM, offering an effective strategy for enhancing drug delivery across the BBB and providing a scientific foundation for the use of exosomes in the treatment of GBM and other diseases.

The challenges of using fish cells for cultivated seafood production

Continuing population growth is increasing nutritional demand and applying pressure to the world's finite resources. The current food systems struggle with sustainability, especially regarding protein sources. To address this, organisations have invested in developing novel sources of protein, such as lab-grown cultivated foods. Most of these efforts have focussed on the cultivated meat industry but neglect the emerging cultivated seafood industry. Arguably, seafood has a greater impact on protein availability and sustainability and should be a priority. Nonetheless, several technical barriers exist to produce cultivated seafood, and include a lack of established cell lines and specialised cell growth medium, that is affordable and sustainable. In addition, the application of this technology is difficult, due to public perception, ethical considerations, taste and food safety hurdles. Herein, we review the barriers that must be overcome by research institutions, companies, and stakeholders so that products can be introduced to the mainstream consumer market.

Development of a biomarker panel for cell characterization intended for cultivated meat

Cultivated meat has in recent years been suggested as a sustainable alternative to produce meat at large-scale. Several aspects of cultivated meat production have demonstrated significant progress. However, there are still many questions regarding the cell culture, media composition, and the production itself to be answered and optimized. Finding good starter cell populations is a challenge to address and requires robust tools to characterize the cell populations. Detailed analysis is required to identify each type of cell within the skeletal muscle niche leads to optimized cultivated meat production at large-scale. In this study, we developed a set of biomarkers, using digital droplet PCR (ddPCR) and Immunofluorescence (IF) staining, to identify specific cell types within a heterogeneous cell population isolated from skeletal muscle tissue. We showed that combining Neural Cell Adhesion Molecule (NCAM), Calponin 1 (CNN1), and Fibronectin (FN), can be a powerful approach to predict the growth of skeletal myotubes, smooth muscle mesenchymal cells (SMMCs), and myofibroblasts, respectively. Moreover, early cell-cell interactions of fibroblastic cells were observed to be triggered through thin actin filaments containing CNN1 protein, to form, subsequently, myofibroblast networks. Besides, Myogenic Differentiation 1 (MyoD) is the key marker to detect skeletal muscle growth, whereas Myogenic Factor 5 (MyF5) can be expressed in myogenic and non-myogenic cells. MyF5 was detected at differentiation stages within the myotube nuclei, suggesting an unknown role during myotube formation.

Milk whey as a sustainable alternative growth supplement to fetal bovine serum in muscle cell culture

In vitro meat cultivation, a cutting-edge innovation in food science, may represent a more sustainable and ethical source of animal proteins compared with conventionally grown meat. An important challenge for meat cultivation lies in eliminating the use of fetal bovine serum (FBS) in cell culture media due to ethical concerns. Milk whey is a nutrient-rich liquid portion of the milk, derived as a byproduct of dairy industry. Similar to FBS, whey contains proteins that are crucial for nutrition, cell adhesion, and biomolecular transport. In this study, we investigated whether whey proteins (WP) can replace FBS in supporting muscle cell cultivation, using the C2C12 myoblast model. Accordingly, under serum-free conditions, cells were treated with 2 WP mixtures, grouping high (β-LG 1.25%, α-LA 1.25%, BSA 1.25%) and low (β-LG 0.07%, α-LA 0.15%, BSA 0.15%) selected concentrations of individual proteins that positively affected cell growth in a preceding dose-response study. Cells cultured in only basal Dulbecco's Modified Eagle Medium were included as a negative control, and cells cultured in 10% FBS as a positive control. Cells were maintained in the treatment media for 48 h (d 1 and 2) to support myoblast proliferation. Subsequently, all the treatments were replaced with a standard low mitogenic 2% horse serum (HS) medium until full differentiation (d 6). The treatment effects on morphology, viability, and lactate dehydrogenase release were assessed after d 1, 2, and 6, respectively. The results showed that WP stimulated cell proliferation under serum-free culture conditions, similar to the FBS control, and subsequently facilitated myotube formation when the WP or FBS treatments were switched to HS medium. After differentiation, these cells also exhibited increased expression of cell differentiation markers such as creatine kinase and citrate synthase and underwent morphological changes from spindle-shaped cells to fused elongated myotubes, in contrast to the negative control. This study demonstrates that WP are a promising and sustainable alternative for considerably replacing FBS-based growth supplements for use in cultivated animal products.

Towards more realistic cultivated meat by rethinking bioengineering approaches

Cultivated meat (CM) refers to edible lab-grown meat that incorporates cultivated animal cells. It has the potential to address some issues associated with real meat (RM) production, including the ethical and environmental impact of animal farming, and health concerns. Recently, various biomanufacturing methods have been developed to attempt to recreate realistic meat in the laboratory. We therefore overview recent achievements and challenges in the production of CM. We also discuss the issues that need to be addressed and suggest additional recommendations and potential criteria to help to bridge the gap between CM and RM from an engineering standpoint.

Microbial lysates as low-cost serum replacements in cellular agriculture media formulation

Cultivated meat, the process of generating meat in vitro without sacrificing animals, is a promising alternative to the traditional practice of livestock agriculture. However, the success of this field depends on finding sustainable and economical replacements for animal-derived and expensive fetal bovine serum (FBS) that is typically used in cell culture processes. Here, we outline an effective screening process to vet the suitability of microbial lysates to support the growth of immortalized bovine satellite cells (iBSCs) and mackerel (Mack1) cells. We show that easily producible, low-cost whole-cell lysates from Vibrio natriegens can be used to create serum-free media for the long-term growth of iBSCs. The optimized medium, named "VN40" (basal B8 media containing Vibrio natriegens lysate proteins at 40 µg/mL), outperforms previously established serum-free media while maintaining cell phenotype and myogenicity. Overall, this study shows a novel approach to producing serum-free media for cultivated meat production using microbially-derived lysates.

Recombinant Porcine FGF1 Promotes Muscle Stem Cell Proliferation and Mitochondrial Function for Cultured Meat Production

Cultured meat is an emerging technology with the potential to meet future protein demands while addressing the challenges associated with traditional livestock farming. The production of cultured meat requires efficient, animal component-free in vitro systems for muscle stem cell (MuSC) expansion. Fibroblast growth factor 1 (FGF1) is a critical growth factor that regulates the MuSC function. In this study, we established an efficient method for the soluble expression and purification of recombinant porcine FGF1 (rpFGF1) in Escherichia coli, achieving a yield of 48 mg of purified protein per liter of culture. Treatment with rpFGF1 significantly enhanced the proliferation of porcine MuSC under serum-free conditions. Furthermore, rpFGF1 induced mitochondrial fission and mitophagy by activating the ERK-dependent phosphorylation of DRP1 at Ser616, resulting in improved mitochondrial function and proliferation capacity in porcine MuSC. These findings highlight the potential of rpFGF1 in the development of serum-free media for scalable and sustainable cultured meat production.

Exploring cost reduction strategies for serum free media development

Cultivated meat production offers solutions in addressing global food security and sustainability challenges. However, serum-free media (SFM) used in cultivating the cells are expensive, contributing to at least 50% of variable operating costs. This review explores technologies for cost-effective SFM, focusing on reducing cost from using growth factors and recombinant proteins, using affordable raw materials for basal media, and implementing cost-saving measures like media recycling and reducing waste build-up.

Grifola frondosa extract as a fetal bovine serum supplement for the culture of bovine muscle satellite cells under low serum conditions

Expensive fetal bovine serum (FBS) is a major obstacle to the production of cultivated meat. However, because FBS substitutes do not sufficiently induce cell proliferation, a good alternative is to reduce the amount of FBS and use ingestible additives to promote cell proliferation. In this study, Grifola frondosa extract (GFE) was used to investigate its potential as an additive to promote myogenesis of bovine muscle satellite cells from Hanwoo cattle under low serum conditions (10 % FBS). GFE treated with 10 % FBS only during the proliferation period not only increased cell proliferation and related biomarkers in a concentration-dependent manner (0.78-12.5 μg/mL), but also increased cell differentiation. Additionally, differentiation was promoted when cells were with GFE treated only during the differentiation period. Especially GFE at 12.5 µg/mL induced significantly higher proliferation and differentiation rates than 20 % FBS medium. In particular, compared to treatment alone in the proliferation or differentiation periods, GFE treatment in both periods contributed to an increase in the differentiation rate and significantly enhanced total protein production. The integration of GFE into cultivated meat production presents a promising approach to reducing FBS dependence, lowering costs, and enhancing scalability, aligning with sustainability and consumer acceptance goals.

Increasing sustainability and reproducibility of in vitro toxicology applications: serum-free cultivation of HepG2 cells

Fetal Bovine Serum (FBS) is an important ingredient in cell culture media and the current standard for most cells in vitro. However, the use of FBS is controversial for several reasons, including ethical concerns, political, and societal pressure, as well as scientific problems due to the undefined and variable nature of FBS. Nevertheless, scientists hesitate to change the paradigm without solid data de-risking the switch of their assays to alternatives. In this study, HepG2 cells, a human hepatoblastoma cell line commonly used to study drug hepatotoxicity, were adapted to serum-free conditions by using different commercially available media and FBS replacements. After transition to these new culture conditions, the success of adaptation was determined based on cell morphology and growth characteristics. Long-term culturing capacity for each medium was defined as the number of passages HepG2 cells could be cultured without any alterations in morphology or growth behavior. Two media (Advanced DMEM/F12 from ThermoFisher and TCM® Serum Replacement from MP Biomedicals) showed a long-term cultivation capacity comparable to media containing FBS and were selected for further analysis. Both media can be characterized as serum-free, however still contain animal-derived components: bovine serum albumin (both media) and bovine transferrin (only TCM® serum replacement). To assess the functionality of the cells cultivated in either of the two media, HepG2 cells were treated with reference compounds, specifically selected for their known hepatotoxicity characteristics in man. Different toxicological assays focusing on viability, mitochondrial toxicity, oxidative stress, and intracellular drug response were performed. Throughout the different assays, response to reference compounds was comparable, with a slightly higher sensitivity of serum-free cultivated HepG2 cells when assessing viability/cell death and a lower sensitivity towards oxidative stress. Taken together, the two selected media were shown to support growth, morphology, and function of serum-free cultivated HepG2 cells in the early preclinical safety space. Therefore, these results can serve as a starting point to further optimize culture conditions with the goal to remove any remaining animal-derived components.

Study on the feasibility of using livestock blood as a fetal bovine serum substitute for cultured meat

Fetal bovine serum (FBS) accounts for the largest portion of the cost of cultured meat production or cell culture experiments and is highly controversial in terms of animal welfare because it is taken from the fetus of a pregnant cow during slaughtering. Nevertheless, FBS is the most important supplement in the cell culture manufacturing process. This study aimed to develop an FBS substitute from slaughterhouse waste blood to reduce the cost of FBS in cultured meat production through various experiments. Our study successfully demonstrated that adult livestock blood obtained from slaughterhouses can effectively replace FBS. Our substitute, when cultured with bovine myosatellite cells, demonstrated cell growth that was either equivalent to or superior to that of commercial FBS. In the process of muscle generation through differentiation, the substitutes from bovine and chicken formed 70%-75% more bovine muscle compared to the control group using FBS. Furthermore, using the FBS substitute can reduce cell culture costs by approximately 61% compared to using commercial FBS. Therefore, the groundbreaking FBS substitute will not only contribute to the development of technology to mass-produce cultured meat using livestock byproducts but will also lower the production cost of media for experimental cell culture or vaccine production.

Recent advances in scaffolding biomaterials for cultivated meat

The emergence of cultivated meat provides a sustainable and ethical alternative to traditional animal agriculture, highlighting its increasing importance in the food industry. Biomaterial scaffolds are critical components in cultivated meat production for enabling cell adhesion, proliferation, differentiation, and orientation. While there's extensive research on scaffolding biomaterials, applying them to cultivated meat production poses distinct challenges, with each material offering its own set of advantages and disadvantages. This review summarizes the most recent scaffolding biomaterials used in the last five years for cell-cultured meat, detailing their respective advantages and disadvantages. We suggest future research directions and provide recommendations for scaffolds that support scalable, cost-effective, and safe high-quality meat production. Additionally, we highlight commercial challenges cultivated meat faces, encompassing bioreactor design, cell culture mediums, and regulatory and food safety issues. In summary, this review provides a comprehensive guide and valuable insights for researchers and companies in the field of cultivated meat production.

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.

Comparison of secreted miRNAs and proteins during proliferation and differentiation of bovine satellite cells in culture implies potential roles in regulating myogenesis

Cultivated meat is an emerging new technology to produce sustainable meat for the future. The common approach for cultivated meat, is the isolation of satellite cells from donor animals, followed by in vitro proliferation and differentiation into primitive muscle fibers. The transformation of satellite cells into myofibers is tightly orchestrated by intra-cellular signaling, while the inter-cellular signaling is less well understood. Thus, the current study was conducted to map the secretion of potential signaling molecules (MicroRNAs and proteins) during proliferation and differentiation. Primary cultures of satellite cells were grown to 50% and 80% confluence, representing the proliferative phase or serum-starved for 1 and 3 days to induce differentiation. Post incubation in FBS-free media, the media were collected and analyzed for miRNA and protein content using gene-arrays and LC-MS/MS, respectively. When comparing the miRNA secretome at 50% and 80% confluence, we observed four differentially expressed miRNA, while only five were differentially expressed when comparing Day 1 to Day 3. A subsequent in silico analysis suggested that pathways of importance for myogenesis, e.g., MAPK and AMPK signaling, could be regulated by the secreted miRNAs. In addition, >300 proteins were secreted, including insulin-like growth factor 1 binding proteins 2, 3, 4, 5 and 6. In conclusion, this study demonstrated differential secretion of several miRNAs and proteins during both proliferation and differentiation of bovine satellite cells in vitro.

Development of a serum-free medium for myoblasts long-term expansion and 3D culture for cell-based meat

Cell-based meat technology provides an effective method to meet the demand for meat, while also posing a huge challenge to the expansion of myoblasts. It is difficult to develop serum-free medium suitable for long-term culture and large-scale expansion of myoblasts, which causes limited understanding of myoblasts expansion. Therefore, this study used C2C12 myoblasts as model cells and developed a serum-free medium for large-scale expansion of myoblasts in vitro using the Plackett-Burman design. The serum-free medium can support short-term proliferation and long-term passage of C2C12 myoblasts, while maintaining myogenic differentiation potential well, which is comparable to those of growth medium containing 10% fetal bovine serum. Based on the C2C12 myoblasts microcarriers serum-free culture system established in this study, the actual expansion folds of myoblasts can reach 43.55 folds after 7 days. Moreover, cell-based meat chunks were preliminarily prepared using glutamine transaminase and edible pigments. The research results provide reference for serum-free culture and large-scale expansion of myoblasts in vitro, laying the foundation for cell-based meat production. PRACTICAL APPLICATION: This study developed a serum-free medium suitable for long-term passage of myoblasts and established a microcarrier serum-free culture system for myoblasts, which is expected to solve the problem of serum-free culture and large-scale expansion of myoblasts in cell culture meat production.

The Comparison of Commercial Serum-Free Media for Hanwoo Satellite Cell Proliferation and the Role of Fibroblast Growth Factor 2

Fetal bovine serum (FBS), which contains various nutrients, comprises 20% of the growth medium for cell-cultivated meat. However, ethical, cost, and scientific issues, necesitates identification of alternatives. In this study, we investigated commercially manufactured serum-free media capable of culturing Hanwoo satellite cells (HWSCs) to identify constituent proliferation enhancing factors. Six different serum-free media were selected, and the HWSC proliferation rates in these serum-free media were compared with that of control medium supplemented with 20% FBS. Among the six media, cell proliferation rates were higher only in StemFlexTM Medium (SF) and Mesenchymal Stem Cell Growth Medium DXF (MS) than in the control medium. SF and MS contain high fibroblast growth factor 2 (FGF2) concentrations, and we found upregulated FGF2 protein expression in cells cultured in SF or MS. Activation of the fibroblast growth factor receptor 1 (FGFR1)-mediated signaling pathway and stimulation of muscle satellite cell proliferation-related factors were confirmed by the presence of related biomarkers (FGFR1, FRS2, Raf1, ERK, p38, Pax7, and MyoD) as indicated by quantitative polymerase chain reaction, western blotting, and immunocytochemistry. Moreover, PD173074, an FGFR1 inhibitor suppressed cell proliferation in SF and MS and downregulated related biomarkers (FGFR1, FRS2, Raf1, and ERK). The promotion of cell proliferation in SF and MS was therefore attributed to FGF2, which indicates that FGFR1 activation in muscle satellite cells may be a target for improving the efficiency of cell-cultivated meat production.