ABSTRACT
PURPOSE: The original aim of the study was to determine, in a double-blind 3-arm crossover human trial (n = 7), the effect of supplemental levels of iron (25 mg) and zinc (30 mg) on ß-carotene (synthetic) bioavailability (10 h postprandial). However, despite the high dose of supplemental ß-carotene (15 mg) consumed with the high fat (18 g), dairy-based breakfast test meal, there was a negligible postprandial response in plasma and triglyceride rich fraction ß-carotene concentrations. We then systematically investigated the possible reasons for this low bioavailability of ß-carotene. METHODS: We determined (1) if the supplemental ß-carotene could be micellised and absorbed by epithelial cells, using a Caco-2 cell model, (2) if the fat from the test meal was sufficiently bioavailable to facilitate ß-carotene bioavailability, (3) the extent to which the ß-carotene could have been metabolised and converted to retinoic acid/retinol and (4) the effect of the test meal matrix on the ß-carotene bioaccessibility (in vitro digestion) and Caco-2 cellular uptake. RESULTS: We found that (1) The supplemental ß-carotene could be micellised and absorbed by epithelial cells, (2) the postprandial plasma triacylglycerol response was substantial (approximately 75-100 mg dL-1 over 10 h), indicating sufficient lipid bioavailability to ensure ß-carotene absorption, (3) the high fat content of the meal (approximately 18 g) could have resulted in increased ß-carotene metabolism, (4) ß-carotene bioaccessibility from the dairy-based test meal was sixfold lower (p < 0.05) than when digested with olive oil. CONCLUSION: The low ß-carotene bioavailability is probably due to a combination of the metabolism of ß-carotene to retinol by BCMO1 and interactions of ß-carotene with the food matrix, decreasing the bioaccessibility. TRAIL REGISTRATION: The human trail was retrospectively registered (ClinicalTrail.gov ID: NCT05840848).
ABSTRACT
Neurotoxic phenomena are among the most common side effects of cytotoxic agents. The development of chemotherapy-induced polyneuropathy (CIPN) is a well-recognized adverse reaction in the peripheral nervous system, while changes of cognitive functions (post-chemotherapy cognitive impairment (PCCI)) are more diffuse and have only recently drawn scientific interest. PCCI in patients most often displays as short-term memory loss, reduced multitasking ability or deficits in language. Not least, due to a lack of preclinical human model systems, the underlying molecular mechanisms are poorly understood, and treatments are missing. We thus investigated whether induced pluripotent stem cell (iPSC)-derived brain organoids can serve as a human model system for the study of chemotherapy induced central nervous system toxicity. We robustly generated mature brain organoids from iPSC-derived neuronal precursor cells (NPC), which showed a typical composition with 1) dividing NPCs forming ventricle like structures 2) matured neurons and 3) supporting glial cells closer to the surface. Furthermore, upon stimulation the brain organoids showed functional signaling. When exposed to increasing concentrations of paclitaxel, a frequently used chemotherapy drug, we observed time dependent neurotoxicity with an EC50 of 153 nM, comparable to a published murine model system. Histological analysis after paclitaxel exposure demonstrated dose dependent apoptosis induction and reduced proliferation in the organoids with further Western blot analyses indicating the degradation of neuronal calcium sensor one protein (NCS-1) and activation of Caspase-3. We could also provide evidence that paclitaxel treatment negatively affects the pool of neuronal and astrocyte precursor cells as well as mature neurons. In summary our data suggests that human iPSC derived brain organoids are a promising preclinical model system to investigate molecular mechanisms underlying PCCI and to develop novel prevention and treatment strategies.
