Ida Cariati

Space colonization represents the most insidious challenge for mankind, as numerous obstacles affect the success of space missions. Specifically, the absence of gravitational forces leads to systemic physiological alterations, with particular emphasis on the musculoskeletal system. Indeed, astronauts exposed to spaceflight are known to report a significant impairment of bone microarchitecture and muscle mass, conditions clinically defined as osteoporosis and sarcopenia. In this context, space medicine assumes a crucial position, as the development of strategies to prevent and/or counteract weightlessness-induced alterations appears to be necessary. Furthermore, the opportunity to study the biological effects induced by weightlessness could provide valuable information regarding adaptations to spaceflight and suggest potential treatments that can preserve musculoskeletal health under microgravity conditions. Noteworthy, improving knowledge about the latest scientific findings in this field of research is crucial, as is thoroughly investigating the mechanisms underlying biological adaptations to microgravity and searching for innovative solutions to counter spaceflight-induced damage. Therefore, this narrative study review, performed using the MEDLINE and Google Scholar databases, aims to summarize the most recent evidence regarding the effects of real and simulated microgravity on the musculoskeletal system and to discuss the effectiveness of the main defence strategies used in both real and experimental settings.

Osteosarcopenia (OSP) is a geriatric syndrome characterized by the coexistence of osteoporosis and sarcopenia and associated with an increased risk of fragility fractures, disability, and mortality. For patients with this syndrome, musculoskeletal pain represents the most significant challenge since, in addition to limiting the individual’s functionality and promoting disability, it has a huge psychological burden involving anxiety, depression, and social withdrawal. Unfortunately, the molecular mechanisms involved in the development and persistence of pain in OSP have not yet been fully elucidated, although immune cells are known to play a key role in these processes. Indeed, they release several molecules that promote persistent inflammation and nociceptive stimulation, resulting in the gating of ion channels responsible for the generation and propagation of the noxious stimulus. The adoption of countermeasures to counteract the OSP progression and reduce the algic component appears to be necessary, providing patients with a better quality of life and greater adherence to treatment. In addition, the development of multimodal therapies, based on an interdisciplinary approach, appears to be crucial, combining the use of anti-osteoporotic drugs with an educational programme, regular physical activity, and proper nutrition to eliminate risk factors. Based on this evidence, we conducted a narrative review using the PubMed and Google Scholar search engines to summarize the current knowledge on the molecular mechanisms involved in the pain development in OSP and the potential countermeasures to be taken. The lack of studies addressing this topic highlights the need to conduct new research into the resolution of an ever-expanding social problem.

SARS-CoV-2 has caused a global pandemic and an unprecedented public health crisis, infecting more than 580 million people worldwide. Moreover, recent evidence has suggested the emergence of a new syndrome known as Long-COVID, a term used to describe a diverse set of physical and mental symptoms that persist after a diagnosed SARS-CoV-2 infection. Epidemiological data have identified myalgias, muscle and joint dysfunction, and bone fragility as common sequelae in patients with moderate and severe forms of this disease. Significant musculoskeletal dysfunction has also been detected in some healed patients, although knowledge about pathophysiological mechanisms of Long-COVID is still rather scarce. In this context, SARS-CoV-2 infection has been suggested to amplify the effects of aging on the musculoskeletal system by aggravating the osteosarcopenic state. Based on this evidence, our review focused on the muscle and bone tissue alterations induced by SARS-CoV-2 infection and Long-COVID, summarizing the current knowledge on the underlying biological mechanisms and highlighting the need for a multidisciplinary approach to predict the musculoskeletal targets and long-term consequences of COVID-19 disease.