Recombinant irisin prevents cell death and mineralization defects induced by random positioning machine exposure in primary cultures of human osteoblasts: A promising strategy for the osteoporosis treatment

Abstract

Spaceflight exposure, like prolonged skeletal unloading, is known to result in significant bone loss, but the molecular mechanisms responsible are still partly unknown. This impairment, characterizing both conditions, suggests the possibility of identifying common signalling pathways and developing innovative treatment strategies to counteract the bone loss typical of astronauts and osteoporotic patients. In this context, primary cell cultures of human osteoblasts derived from healthy subjects and osteoporotic patients were exposed to random positioning machine (RPM) to reproduce the absence of gravity and to exacerbate the pathological condition, respectively. The duration of exposure to RPM was 3 or 6 days, with the aim of determining whether a single administration of recombinant irisin (r-irisin) could prevent cell death and mineralizing capacity loss. In detail, cellular responses were assessed both in terms of death/survival, by MTS assay, analysis of oxidative stress and caspase activity, as well as the expression of survival and cell death proteins, and in terms of mineralizing capacity, by investigating the pentraxin 3 (PTX3) expression. Our results suggest that the effects of a single dose of r-irisin are maintained for a limited time, as demonstrated by complete protection after 3 days of RPM exposure and only partial protection when RPM exposure was for a longer time. Therefore, the use of r-irisin could be a valid strategy to counteract the bone mass loss induced by weightlessness and osteoporosis. Further studies are needed to determine an optimal treatment strategy based on the use of r-irisin that is fully protective even over very long periods of exposure and/or to identify further approaches to be used in a complementary manner.

Microgravity and Musculoskeletal Health: What Strategies Should Be Used for a Great Challenge?

“…In addition, r-irisin was able to inhibit the expression of the senescence marker p53 and the pro-apoptotic marker Bax, confirming the role of this myokine in counteracting weightlessness-induced cell death [150]. Finally, Cariati et al recently investigated the efficacy of a single administration of r-irisin in primary cultures of human osteoblasts exposed to RPM for three or six days [151]. Interestingly, cells treated with r-irisin during three-day RPM exposure showed significant protection from apoptotic death, in terms of cell viability, intracellular ROS production, and ratio of apoptotic markers, as well as full preservation of mineralizing capacity, as assessed by PTX3 expression.…”

“…Interestingly, cells treated with r-irisin during three-day RPM exposure showed significant protection from apoptotic death, in terms of cell viability, intracellular ROS production, and ratio of apoptotic markers, as well as full preservation of mineralizing capacity, as assessed by PTX3 expression. However, a single administration of r-irisin was not sufficient to counteract the damage induced by RPM exposure for a longer time, suggesting the need for repeated administration or the development of complementary strategies aimed at corroborating the action of r-irisin [151].…”

Stromal Lineage Precursors from Rodent Femur and Tibia Bone Marrows after Hindlimb Unloading: Functional Ex Vivo Analysis

“…In vitro simulation using Random Positioning Machine (RPM) needs to be mentioned in respect of stromal lineage fate under microgravity. As it was demonstrated, RPM exposure provoked morphological and metabolic alterations of human osteoblasts and murine MC3T3-E1 cells characterized by increased levels of reactive oxygen species, slowdown of the proliferative rate, or even cell death, mineralizing capacity loss, while Irisin or antioxidant Trolox could prevent this damage [18,19]. Above mentioned data indicate the potency of Irisin and antioxidants to counteract the musculoskeletal impairment caused by unloading.…”

Trolox and recombinant Irisin as a potential strategy to prevent neuronal damage induced by random positioning machine exposure in differentiated HT22 cells

“…In detail, all cell samples were washed several times with PBS and incubated with 10 μM H 2 DCFDA for 40 min at 37°C in the dark after RPM exposure. A plate reader (Spark Multimode Microplate Reader-Tecan, Austria) was used to measure the mean fluorescence intensity of each experimental group, representing the intracellular ROS level [ 38 ]. For each condition, the experiment was conducted in triplicate ( n = 15 from N = 5 experiments).…”