In contrast to Hill equations, which are not available for enzymatic reactions, which only calculate relative concentrations, and which only work for one reaction in isolation, the psf system calculates enzymatic and complex formation reactions in a complex systemic environment using absolute concentrations.
In a mouse model of young and old mice sharing the circulatory system (heterochronic parabiosis model) aged SCs were rejuvenated by exposure to a young systemic environment suggesting that the tissue-specific stem cells retain their proliferative potential, but that the aged systemic environment prevents full activation.
This hypothesis has been clearly validated by parabiotic experiments, the union of two organisms that share the circulatory system, demonstrating the rejuvenation of aged progenitor cells by exposure to a young systemic environment (Conboy et al. 2005).
Rejuvenation of aged progenitor cells by exposure to a young systemic environment.
McAllister SS, Weinberg RA (2014) The tumour-induced systemic environment as a critical regulator of cancer progression and metastasis.
McAllister, S. S. & Weinberg, R. A. The tumour-induced systemic environment as a critical regulator of cancer progression and metastasis.
LbL assembly of polypeptides effectively prevented exposure of PTX to the systemic environment and thereby inhibited drug-induced hemolysis.
They aim for a multidimensional function design striving to address the demands of the local and systemic environment, in addition to patient comfort and quality of life.
This paper advances the development of these systems by establishing them as drug carriers, with the means to control drug release in a systemic environment and retard particle clearance from circulation, promoting improved biodistribution of the drug-containing system.
The present study uses a controlled LbL process to create a multidrug-loaded nanoplatform capable of promoting blood circulation time, biodistribution profile and controlling drug release in the dynamic systemic environment.
We show that muscle stem cells (satellite cells) from aged mice tend to convert from a myogenic to a fibrogenic lineage as they begin to proliferate and that this conversion is mediated by factors in the systemic environment of the old animals.
