Exploring of exosomes in pathogenesis, diagnosis and therapeutic of osteonecrosis of the femoral head: the mechanisms and signaling pathways.

Osteonecrosis of the femoral head (ONFH) is a refractory disease affecting young adults, resulting in severe hip pain, femoral head collapse, and disabling dysfunction. By far, the underlying mechanism of its pathology is unclear, and still lack of a mature and effective treatment. Exosomes, a regulator of cell-cell communication, their cargos may vary in response to different physiological or pathological conditions. To date, many studies have demonstrated that exosomes have the potential to become a diagnostic marker and therapeutic agent in many human diseases including ONFH. As a cell-free therapeutic agent, exosomes are becoming a promising tool within this field due to their crucial role in osteogenesis and angiogenesis in recent decades. Usually, exosomes from ONFH tissues could promote ONFH damage, while stem cells derived exosomes could delay diseases and repair femoral head necrosis. Herein, we describe the properties of exosomes, discuss its effect on pathogenesis, diagnosis, and treatment potential in ONFH, and examine the involvement of different signaling pathways. We also propose our suggestions for the future research of exosomes in ONFH field and hope to provide a potential therapeutic strategy for patients with ONFH.

Dynamics, statistics, and task allocation of foraging ants.

Ant foraging is one of the most fascinating examples of cooperative behavior observed in nature. It is well studied from an entomology viewpoint, but there is currently a lack of mathematical synthesis of this phenomenon. We address this by constructing an ant foraging model that incorporates simple behavioral rules within three task groups of the ant colony during foraging (foragers, transporters, and followers), pheromone trails, and memory effects. The motion of an ant is modeled as a discrete correlated random walk, with a characteristic zigzag path that is congruent with experimental data. We simulate the foraging cycle, which consists of ants searching for food, transporting food, and depositing chemical trails to recruit and orient more ants (en masse) to the food source. This allows us to gain insights into the basic mechanism of the cooperative interactions between ants and the dynamical division of labor within an ant colony during foraging to achieve optimal efficiency. We observe a disorder-order phase transition from the start to the end of a foraging process, signaling collective motion at the population level. Finally, we present a set of time delay ODEs that corroborates with numerical simulations.