Spontaneous physical activity down-regulates Pax7 in cancer cachexia

Emerging evidence suggests that the muscle microenvironment plays a prominent role in cancer cachexia. We recently showed that NF-kB - induced Pax7 overexpression impairs the myogenic potential of muscle precursors in cachectic mice, suggesting that lowering Pax7 expression may be beneficial in cancer cachexia. We evaluated the muscle regenerative potential after acute injury in C26 colon carcinoma tumor-bearing mice and healthy controls. Our analyses confirmed that the delayed muscle regeneration observed in muscles form tumor-bearing mice was associated with a persistent local inflammation and Pax7 overexpression. Physical activity is known to exert positive effects on cachectic muscles. However, the mechanism by which a moderate voluntary exercise ameliorates muscle wasting is not fully elucidated. To verify if physical activity affects Pax7 expression, we hosted control and C26-bearing mice in wheel-equipped cages and we found that voluntary wheel running down-regulated Pax7 expression in muscles from tumor-bearing mice. As expected, down-regulation of Pax7 expression was associated with a rescue of muscle mass and fiber size. Our findings shed light on the molecular basis of the beneficial effect exerted by a moderate physical exercise on muscle stem cells in cancer cachexia. Furthermore, we propose voluntary exercise as a physiological tool to counteract the over-expression of Pax7observed in cancer cachexia

Molecular, cellular and physiological characterization of the cancer cachexia-inducing C26 colon carcinoma in mouse

BACKGROUND: The majority of cancer patients experience dramatic weight loss, due to cachexia and consisting of skeletal muscle and fat tissue wasting. Cachexia is a negative prognostic factor, interferes with therapy and worsens the patients' quality of life by affecting muscle function. Mice bearing ectopically-implanted C26 colon carcinoma are widely used as an experimental model of cancer cachexia. As part of the search for novel clinical and basic research applications for this experimental model, we characterized novel cellular and molecular features of C26-bearing mice. METHODS: A fragment of C26 tumor was subcutaneously grafted in isogenic BALB/c mice. The mass growth and proliferation rate of the tumor were analyzed. Histological and cytofluorometric analyses were used to assess cell death, ploidy and differentiation of the tumor cells. The main features of skeletal muscle atrophy, which were highlighted by immunohistochemical and electron microscopy analyses, correlated with biochemical alterations. Muscle force and resistance to fatigue were measured and analyzed as major functional deficits of the cachectic musculature. RESULTS: We found that the C26 tumor, ectopically implanted in mice, is an undifferentiated carcinoma, which should be referred to as such and not as adenocarcinoma, a common misconception. The C26 tumor displays aneuploidy and histological features typical of transformed cells, incorporates BrdU and induces severe weight loss in the host, which is largely caused by muscle wasting. The latter appears to be due to proteasome-mediated protein degradation, which disrupts the sarcomeric structure and muscle fiber-extracellular matrix interactions. A pivotal functional deficit of cachectic muscle consists in increased fatigability, while the reported loss of tetanic force is not statistically significant following normalization for decreased muscle fiber size. CONCLUSIONS: We conclude, on the basis of the definition of cachexia, that ectopically-implanted C26 carcinoma represents a well standardized experimental model for research on cancer cachexia. We wish to point out that scientists using the C26 model to study cancer and those using the same model to study cachexia may be unaware of each other's works because they use different keywords; we present strategies to eliminate this gap and discuss the benefits of such an exchange of knowledge

The vulnerability of the human being in a technological environment: the need for protective regulation

The article aims to highlight how the natural person, coming into contact and working with digital environments or with technological instruments, is exposed to various types of damage risks. This requires considering the human being always vulnerable in the digital environment, regardless of the minor unit or a disability

ROLE OF PHYSICAL ACTIVITY AND OXIDATIVE STRESS IN CACHEXIA

Cachexia is a muscle wasting syndrome leading to muscle atrophy and weakness associated to most chronic diseases, including cancer, acquired immune deficiency syndrome, rheumatoid arthritis, chronic obstructive pulmonary disease, renal failure. Cachexia is a critical issue in the comprehensive approach to chronic patients since it affects morbidity, mortality and quality of life. Physical exercise has important effects on secondary prevention or intervention against several diseases. Although there are good reasons to recommend regular physical activity in patient populations, recommending exercise is not a straightforward endeavor in patients with chronic diseases. Oxidative stress may be a pivotal etiological factor in the onset of cachexia. Expression of muscle specific ubiquitin ligase responsible for muscle wasting is increased by oxidative stress, whereas nitric oxide may protect against muscle atrophy. Also, endurance exercise causes oxidative stress. Thus the question arises whether to exercise or not to exercise in cachexia

Skeletal muscle damage, regeneration and inflammatory responses in cachexia

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The pro-myogenic environment provided by whole organ scale acellular scaffolds from skeletal muscle.

In the pursuit of a transplantable construct for the replacement of large skeletal muscle defects arising from traumatic or pathological conditions, several attempts have been made to obtain a highly oriented, vascularized and functional skeletal muscle. Acellular scaffolds derived from organ decellularization are promising, widely used biomaterials for tissue engineering. However, the acellular skeletal muscle extra cellular matrix (ECM) has been poorly characterized in terms of production, storage and hoste-donor interactions.We have produced acellular scaffolds at the whole organ scale from various skeletal muscles explanted from mice. The acellular scaffolds conserve chemical and architectural features of the tissue of origin, including the vascular bed. Scaffolds can be sterilely stored for weeks at þ4 C or þ37 C in tissue culture grade conditions. When transplanted in wt mice, the grafts are stable for several weeks, whilst being colonized by inflammatory and stem cells. We demonstrate that the acellular scaffold per se represents a pro-myogenic environment supporting de novo formation of muscle fibers, likely derived from host cells with myogenic potential. Myogenesis within the implant is enhanced by immunosuppressive treatment. Our work highlights the fundamental role of this niche in tissue engineering application and unveils the clinical potential of allografts based on decellularized tissue for regenerative medicine

Decellularized scaffolds from skeletal muscle are a suitable environment for myogenesis in vivo

Background. Skeletal muscle defects arising from traumatic or pathological conditions may require surgical interventions. In our previous studies we described the interactions between a decellularized scaffold derived from a murine skeletal muscle and an isogenic mouse host. Our research is focused on the interaction of the grafted scaffold with other tissues, i.e immune and nervous systems. In addition, we aim to build off-the-shelf, transplantable constructs by culturing myogenic cells into the scaffold before transplantation. Methods. We decellularized Tibialis Anterior muscle of cadaveric origin. The decellularization process was achieved by incubation of dissected muscles in a detergent solution. To replace homologous muscles, we orthotopically transplanted decellularized scaffolds, by suturing them to the host tendon extremities following TA removal. With this approach the constructs were analyzed in regard to histocompatibility, bioactivity, degradability, toxicity in vivo at different times from transplantation. Alternatively, before transplantation the scaffolds were pre-seeded with myogenic cells in vitro. Results and conclusions. The procedure to produce acellular scaffolds from cadaveric skeletal muscles preserves the extracellular matrix and its anatomical pattern. The transplanted acellular scaffold is readily colonized by both inflammatory and myogenic stem cells, as demonstrated by the expression of stem cell markers, followed by the formation of muscle fibers. The latter show centrally located nuclei and express muscle-specific myosin. Cytofluorimetric analysis of the inflammatory cells population shows that CD45+ cells are mostly represented by macrophages, even though T lymphocytes and granulocytes are also present. So likely macrophages play a major role in acellular muscle graft integration and remodeling. Functionality of skeletal muscle is strictly dependent on myofibers spatial orientation and on innervation. Preliminary data suggest the presence of neuro-muscular junctions in the proximity of the cells that populate the grafted scaffold, suggesting the potential for re-innervation of the implant. The integration of the scaffold can likely be boosted by previous myogenic cell colonization, so we delivered satellite cells to the acellular scaffolds and noted the formation of muscle fibers into the construct in culture. Our studies show that scaffolds derived from decellularized muscles are a highly myogenic environment and may represent an innovative tool for skeletal muscle regenerative medicine

Decellularized scaffolds from skeletal muscle are suitable environment for myogenesis in vivo

Background. Skeletal muscle loss secondary to trauma or myopathy may require surgical interventions, i.e. muscle transplant or transposition. Our approach for skeletal muscle tissue engineering is based on a decellularized scaffold derived from a murine skeletal muscle of cadaveric origin. Our goal is the preparation of an implantable scaffold for applications in muscle repair surgical intervention. Methods. We decellularized the Tibialis Anterior (TA) muscle of cadaveric origin from murine hindlimbs. The decellularization process was achieved by incubation of dissected muscles in a detergent solution for different times accordingly to the muscle size. To assess biocompatibility, cell-loaded scaffolds were initially cultured in growth medium (i.e. containing high serum) followed by incubation in a differentiative medium (i.e. containing low serum), and cell viability was assessed by incorporation of the vital dye CMFDA. To replace homologous muscles, we transplanted decellularized scaffolds in vivo, by suturing them to the host tendon extremities following TA removal. The same protocol of transplantation was applied to implants derived from wild type mice in place of the homologous muscle in Nude mice (wt/Nude). With this approach the constructs were analyzed in regard to histocompatibility, bioactivity, degradability, toxicity in vivo at different times from transplantation. Results and discussion. The procedure to produce acellular scaffolds from cadaveric skeletal muscles preserves the extracellular matrix and its anatomical pattern. These scaffolds are suitable for myoblast cell culture in vitro and the cells are viable for several days. Both wt/wt mice and wt/Nude mice transplantation studies demonstrate that scaffolds are biodegradable in vivo in four weeks. Nonetheless, the transplanted acellular scaffold is readily colonized by both inflammatory and myogenic stem cells, as demonstrated by the expression of stem cell markers, followed by the formation of muscle fibers. The latter show centrally located nuclei and express muscle-specific myosin. Our studies represent the first molecular characterization of in vivo bioactivity of scaffolds derived from decellularized muscles and demonstrate that acellular scaffolds represent an innovative tool for the reconstruction of missing muscles