RESUMO
Lipase is a very important digestive enzyme for triglyceride absorption in vivo. The inhibitory activities of 26 dietary flavonoids, including flavone, flavanone, isoflavone and flavanol, on lipase were determined. Flavone exhibited stronger inhibitory activity than other types of flavonoids. Among them, luteolin exhibited the strongest inhibitory activity with IC50 value of 99 ± 11 µM, followed by quercetin and baicalein. The binding affinity of these flavonoids with lipase was investigated by fluorescence titration method. The binding affinity of flavones was stronger than flavanones, and was linearly positively correlated with their inhibitory activity. The binding of flavones on lipase caused the blue-shift of fluorescence, while flavanones caused red-shift. The analysis of structure-activity relationship of flavonoids on lipase revealed that the structure of C ring is very crucial. The hydrogenation of C2=C3 bond and the absence of C=O group in C ring both caused significant decrease of inhibitory activity. Besides, the hydroxylation on ring A and B of flavones increased the activity, while glycosylation weakened the activity. Molecular docking analysis confirmed that C2=C3 bond in C ring of flavones increases the π-conjugation and contributes to maintaining the planarity of flavonoid structure, which favour its Pi-Pi interaction with lipase.
RESUMO
Human umbilical cord mesenchymal stem cells (hUC-MSCs) are a promising candidate for spinal cord injury (SCI) repair owing to their advantages of low immunogenicity and easy accessibility over other MSC sources. However, modest clinical efficacy hampered the progression of these cells to clinical translation. This discrepancy may be due to many variables, such as cell source, timing of implantation, route of administration, and relevant efficacious cell dose, which are critical factors that affect the efficacy of treatment of patients with SCI. Previously, we have evaluated the safety and efficacy of 4 × 106 hUC-MSCs/kg in the treatment of subacute SCI by intrathecal implantation in rat models. To search for a more accurate dose range for clinical translation, we compared the effects of three different doses of hUC-MSCs - low (0.25 × 106 cells/kg), medium (1 × 106 cells/kg) and high (4 × 106 cells/kg) - on subacute SCI repair through an elaborate combination of behavioral analyses, anatomical analyses, magnetic resonance imaging-diffusion tensor imaging (MRI-DTI), biotinylated dextran amine (BDA) tracing, electrophysiology, and quantification of mRNA levels of ion channels and neurotransmitter receptors. Our study demonstrated that the medium dose, but not the low dose, is as efficient as the high dose in producing the desired therapeutic outcomes. Furthermore, partial restoration of the γ-aminobutyric acid type A (GABAA) receptor expression by the effective doses indicates that GABAA receptors are possible candidates for therapeutic targeting of dormant relay pathways in injured spinal cord. Overall, this study revealed that intrathecal implantation of 1 × 106 hUC-MSCs/kg is an alternative approach for treating subacute SCI.
RESUMO
Functional multipotency renders human umbilical cord mesenchymal stem cell (hUC-MSC) a promising candidate for the treatment of spinal cord injury (SCI). However, its safety and efficacy have not been fully understood for clinical translation. In this study, we performed cellular, kinematic, physiological, and anatomical analyses, either in vitro or in vivo, to comprehensively evaluate the safety and efficacy associated with subarachnoid transplantation of hUC-MSCs in rats with subacute incomplete SCI. Concerning safety, hUC-MSCs were shown to have normal morphology, excellent viability, steady proliferation, typical biomarkers, stable karyotype in vitro, and no tumorigenicity both in vitro and in vivo. Following subarachnoid transplantation of hUC-MSCs in the subject rodents, the biodistribution of hUC-MSCs was restricted to the spinal cord, and no toxicity to immune system or organ function was observed. Body weight, organ weight, and the ratio of the latter upon the former between stem cell-transplanted rats and placebo-injected rats revealed no statistical differences. Regarding efficacy, hUC-MSCs could differentiate into osteoblasts, chondrocytes, adipocytes and neural progenitor cells in vitro. While in vivo studies revealed that subarachnoid transplantation of stem cells resulted in significant improvement in locomotion, earlier automatic micturition recovery and reduced lesion size, which correlated with increased regeneration of tracking fiber and reduced parenchymal inflammation. In vivo luminescence imaging showed that a few of the transplanted luciferase-labeled hUC-MSCs tended to migrate towards the lesion epicenter. Shortened latency and enhanced amplitude were also observed in both motor and sensory evoked potentials, indicating improved signal conduction in the damaged site. Immunofluorescent staining confirmed that a few of the administrated hUC-MSCs integrated into the spinal cord parenchyma and differentiated into astrocytes and oligodendrocytes, but not neurons. Moreover, decreased astrogliosis, increased remyelination, and neuron regeneration could be observed. To the best of our knowledge, this preclinical study provides detailed safety and efficacy evidence regarding intrathecal transplantation of hUC-MSCs in treating SCI for the first time and thus, supports its initiation in the following clinical trial.
