As one of the alternatives for livestock meat production, in vitro culturing of meat is currently studied. The generation of bio-artificial muscles from satellite cells has been ongoing for about ...15years, but has never been used for generation of meat, while it already is a great source of animal protein.
In order to serve as a credible alternative to livestock meat, lab or factory grown meat should be efficiently produced and should mimic meat in all of its physical sensations, such as visual appearance, smell, texture and of course, taste. This is a formidable challenge even though all the technologies to create skeletal muscle and fat tissue have been developed and tested. The efficient culture of meat will primarily depend on culture conditions such as the source of medium and its composition. Protein synthesis by cultured skeletal muscle cells should further be maximized by finding the optimal combination of biochemical and physical conditions for the cells. Many of these variables are known, but their interactions are numerous and need to be mapped. This involves a systematic, if not systems, approach. Given the urgency of the problems that the meat industry is facing, this endeavor is worth undertaking. As an additional benefit, culturing meat may provide opportunities for production of novel and healthier products.
► Alternatives to livestock meat production are discussed. ► Cultured meat from satellite cells is promising. ► Efficient production and meat mimicry: essential for cultured meat acceptance. ► Technologies to culture meat are ready to be optimized.
Alternative sources of animal proteins are needed that can be produced efficiently, thereby providing food security with diminished ecological burden. It is feasible to culture beef from bovine ...skeletal muscle stem cells, but the technology is still under development. The aim is to create a beef mimic with equivalent taste, texture, and appearance and with the same nutritional value as livestock‐produced beef. More specifically, there is a need for optimization of protein content and fat content. In addition, scalability of production requires modification of current small‐scale bioreactors to the largest possible scale. The necessary steps and current progress suggest that this aim is achievable, but formal evidence is still required. Similarly, we can be optimistic about consumer acceptance based on initial data, but detailed studies are needed to gain more insight into potential psychological obstacles that could lead to rejection. These challenges are formidable but likely surmountable. The severity of upcoming food‐security threats warrants serious research and development efforts to address the challenges that come with bringing cultured beef to the market.
Due to the considerable environmental impact and the controversial animal welfare associated with industrial meat production, combined with the ever-increasing global population and demand for meat ...products, sustainable production alternatives are indispensable. In 2013, the world's first laboratory grown hamburger made from cultured muscle cells was developed. However, coming at a price of $300.000, and being produced manually, substantial effort is still required to reach sustainable large-scale production. One of the main challenges is scalability. Microcarriers (MCs), offering a large surface/volume ratio, are the most promising candidates for upscaling muscle cell culture. However, although many MCs have been developed for cell lines and stem cells typically used in the medical field, none have been specifically developed for muscle stem cells and meat production. This paper aims to discuss the MCs' design criteria for skeletal muscle cell proliferation and subsequently for meat production based on three scenarios: (1) MCs are serving only as a temporary substrate for cell attachment and proliferation and therefore they need to be separated from the cells at some stage of the bioprocess, (2) MCs serve as a temporary substrate for cell proliferation but are degraded or dissolved during the bioprocess, and (3) MCs are embedded in the final product and therefore need to be edible. The particularities of each of these three bioprocesses will be discussed from the perspective of MCs as well as the feasibility of a one-step bioprocess. Each scenario presents advantages and drawbacks, which are discussed in detail, nevertheless the third scenario appears to be the most promising one for a production process. Indeed, using an edible material can limit or completely eliminate dissociation/degradation/separation steps and even promote organoleptic qualities when embedded in the final product. Edible microcarriers could also be used as a temporary substrate similarly to scenarios 1 and 2, which would limit the risk of non-edible residues.
Cultured meat, in particular beef, is an emerging food technology potentially challenged by issues of consumer acceptance. To understand drivers of consumer acceptance as well as sensory perception ...of cultured meat, we investigated the effect of information content on participants' acceptance of cultured meat in a tasting context. Hundred ninety-three citizens from the Netherlands participated, divided across three age and sex-matched groups which each received information on either societal benefits, personal benefits or information on the quality and taste of cultured meat. They filled out a questionnaire and tasted two pieces of hamburger, labeled 'conventional' or 'cultured', although both pieces were in fact conventional. Sensory analysis of both hamburgers was performed. We observed that provision of information and the tasting experience increased acceptance of cultured meat and that information on personal benefits of cultured meat increased acceptance more than information on quality and taste but not than societal benefits of cultured meat. Previous awareness of cultured meat was the best predictor of its acceptance. In contrast to previous studies, sex and social economic status were not associated with different acceptance rates. Surprisingly, 58% of the respondents were willing to pay a premium for cultured meat of, on average, 37% above the price of regular meat. All participants tasted the 'cultured' hamburger and evaluated its taste to be better than the conventional one in spite of the absence of an objective difference. This is the first acceptance study of cultured meat where participants were offered to eat and evaluate meat that was labeled 'cultured'. We conclude that having positive information importantly improves acceptance and willingness to taste and that the specific content of the information is of subordinate importance. Awareness of cultured meat is the best predictor of acceptance.
Macrophages play a crucial role in all stages of cutaneous wound healing responses and dysregulation of macrophage function can result in derailed wound repair. The phenotype of macrophages is ...influenced by the wound microenvironment and evolves during healing from a more pro-inflammatory (M1) profile in early stages, to a less inflammatory pro-healing (M2) phenotype in later stages of repair. The aim of the current study was to investigate the potential of exogenous administration of M2 macrophages to promote wound healing in an experimental mouse model of cutaneous injury. Bone marrow derived macrophages were stimulated in-vitro with IL-4 or IL-10 to obtain two different subsets of M2-polarized cells, M2a or M2c respectively. Polarized macrophages were injected into full-thickness excisional skin wounds of either C57BL/6 or diabetic db/db mice. Control groups were injected with non-polarized (M0) macrophages or saline. Our data indicate that despite M2 macrophages exhibit an anti-inflammatory phenotype in-vitro, they do not improve wound closure in wild type mice while they delay healing in diabetic mice. Examination of wounds on day 15 post-injury indicated delayed re-epithelialization and persistence of neutrophils in M2 macrophage treated diabetic wounds. Therefore, topical application of ex-vivo generated M2 macrophages is not beneficial and contraindicated for cell therapy of skin wounds.
Objective
Macrophages show extreme heterogeneity and different subsets have been characterized by their activation route and their function. For instance, macrophage subsets are distinct by acting ...differently under pathophysiological conditions such as inflammation and cancer. Macrophages also contribute to angiogenesis, but the role of various specific subsets in angiogenesis has not been thoroughly investigated.
Methods and results
Matrigel supplemented with macrophage subsets induced by IFNγ (M1), IL-4 (M2a) or IL-10 (M2c) was injected subcutaneously in C57BL/6 J mice and analyzed by CD31 staining after 14 days. Increased numbers of endothelial cells and tubular structures were observed in M2-enriched plugs compared to control and other subsets. Additionally, more tubular structures formed in vitro in the presence of M2 macrophages or their conditioned medium. To identify a mechanism for the pro-angiogenic effect, gene expression of angiogenic growth factors was analyzed. Induced expression of basic fibroblast growth factor (
Fgf2
), insulin-like growth factor-1 (
Igf1
), chemokine (C–C motif) ligand 2 (
Ccl2
) and placental growth factor (
Pgf
) was observed in M2 macrophages. Using a blocking antibody of PlGF to inhibit M2c induced angiogenesis resulted in mildly reduced (40 %) tube formation whereas neutralization of FGF-2 (M2a) signaling by sFGFR1-IIIc affected tube formation by nearly 75 %.
Conclusions
These results indicate that macrophages polarized towards an M2 phenotype have a higher angiogenic potential compared to other subsets. Furthermore, we propose FGF signaling for M2a- and PlGF signaling for M2c-induced angiogenesis as possible working mechanisms, yet, further research should elucidate the exact mechanism for M2-induced angiogenesis.
Isolating and maintaining the appropriate stem cell for large scale cell culture is essential in tissue engineering or food production. For bovine satellite cells an optimized isolation and ...purification protocol is lacking and there is also no detailed understanding on the factors that maintain stemness of these cells. Here, we set up a fluorescence-activated cell sorting strategy to enrich bovine satellite cells. We found that p38-MAPK signalling is activated and PAX7 expression is gradually lost during satellite cell proliferation. The p38 inhibitor (SB203580) treatment maintained PAX7 expression but inhibited the fusion of satellite cells in a concentration-dependent way in short-term incubation. The mechanism of p38 inhibition was confirmed by inhibiting canonical p38 signalling, i.e. HSP27. Long-term culture with an appropriate concentration of p38i enhanced the proliferation and PAX7 expression, while the differentiation capacity recovered and was enhanced compared to vehicle control. These studies indicate that bovine satellite cells maintenance depends on cell purity and p38 MAPK signalling. Inhibition of p38 MAPK signaling is a promising strategy to facilitate large scale cell expansion of primary cells for tissue engineering and cultured meat purposes.
Cultured meat is meat for consumption produced in a more sustainable way. It involves cell harvesting and expansion, differentiation into myotubes, construction into muscle fibres and meat ...structuring. We isolated 5.3 × 104 porcine muscle stem cells from 1 g of neonatal pig muscle tissue. According to calculations, we need to expand muscle stem cells 106-107 times to produce 100 g or 1 kg of cultured meat. However, the cells gradually lost the ability to express stemness and mature muscle cell markers (PAX7, MyHC). To tackle this critical issue and maintain cell function during cell expansion, we found that long-term culture with (100 μM) l-Ascorbic acid 2-phosphate (Asc-2P) accelerated cell proliferation while preserving the muscle cell differentiation. We further optimized a scalable PDMS mold. Porcine muscle stem cells formed structurally-organized myotubes similar to muscle fibres in the mold. Asc-2P enhanced porcine muscle cells grown as 3D tissue networks that can produce a relatively large 3D tissue networks as cultured meat building blocks, which showed improved texture and amino acid content. These results established a realistic workflow for the production of cultured meat that mimics the pork meat structurally and is potentially scalable for industry.
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