Bioavailability of insulin detemir and human insulin at the level of peripheral interstitial fluid in humans, assessed by open-flow microperfusion

Comparative Study of Dermal Pharmacokinetics Between Topical Drugs Using Open Flow Microperfusion in a Pig Model

PURPOSE

Accurate methods to determine dermal pharmacokinetics are important to increase the rate of clinical success in topical drug development. We investigated in an in vivo pig model whether the unbound drug concentration in the interstitial fluid as determined by dermal open flow microperfusion (dOFM) is a more reliable measure of dermal exposure compared to dermal biopsies for seven prescription or investigational drugs. In addition, we verified standard dOFM measurement using a recirculation approach and compared dosing frequencies (QD versus BID) and dose strengths (high versus low drug concentrations).

METHODS

Domestic pigs were topically administered seven different drugs twice daily in two studies. On day 7, drug exposures in the dermis were assessed in two ways: (1) dOFM provided the total and unbound drug concentrations in dermal interstitial fluid, and (2) clean punch biopsies after heat separation provided the total concentrations in the upper and lower dermis.

RESULTS

dOFM showed sufficient intra-study precision to distinguish interstitial fluid concentrations between different drugs, dose frequencies and dose strengths, and had good reproducibility between studies. Biopsy concentrations showed much higher and more variable values. Standard dOFM measurements were consistent with values obtained with the recirculation approach.

CONCLUSIONS

dOFM pig model is a robust and reproducible method to directly determine topical drug concentration in dermal interstitial fluid. Dermal biopsies were a less reliable measure of dermal exposure due to possible contributions from drug bound to tissue and drug associated with skin appendages.

(Pro)renin receptor and insulin signaling regulate cell proliferation in MCF-7 breast cancer cells

(Pro)renin receptor [(P)RR] is related to both the renin-angiotensin system and V-ATPase with various functions including stimulation of cell proliferation. (P)RR is implicated in the pathophysiology of diabetes mellitus and cancer. Hyperinsulinemia is observed in obesity-related breast cancer. However, the relationship between (P)RR and insulin has not been clarified. We have therefore studied the effect of insulin on (P)RR expression, cell viability, and AKT phosphorylation under the conditions with and without (P)RR knockdown. Effects of insulin were studied in a human breast cancer cell line, MCF-7. Cell proliferation assay was performed by WST-8 assay. (P)RR expression was suppressed by (P)RR-specific siRNAs. The treated cells were analyzed by western blotting and real-time quantitative PCR analysis. Insulin stimulated proliferation of MCF-7 cells and increased (P)RR protein expression, but not (P)RR mRNA levels. Moreover, autophagy flux was suppressed by insulin. Suppression of (P)RR expression reduced cell number of MCF-7 cells and AKT phosphorylation significantly in both the presence and the absence of insulin, indicating that (P)RR is important for cell viability and AKT phosphorylation. In conclusion, insulin upregulates the level of (P)RR protein, which is important for cell viability, proliferation, AKT phosphorylation, and autophagy in breast cancer cells.

Optimization of topical formulations using a combination of in vitro methods to quantify the transdermal passive diffusion of drugs

This paper describes a new approach to the early-stage optimization of topical products and selection of lead formulation candidates. It demonstrates the application of open flow microperfusion in vitro in conjunction with the Franz diffusion cell to compare time-resolved, 24-hour profiles of diclofenac passive diffusion through all skin layers (including the skin barrier, dermis, and subcutis) resulting from nine topical formulations of different composition. The technique was successfully validated for in vitro sampling of diclofenac in interstitial fluid. A multi-compartmental model integrating the two datasets was analyzed and revealed that the passive diffusion of diclofenac through the dermis and subcutis does not correlate with its diffusion through the skin barrier and cannot be predicted using Franz diffusion cell data alone. The combined application of the two techniques provides a new, convenient tool for product development and selection enabling the comparison of topical formulation candidates and their impact on drug delivery through all skin layers. This approach can also generate the experimental data required to improve the robustness of mechanistic PBPK models, and when combined with clinical sampling via open flow microperfusion - for the development of better in vivo-in vitro correlative models.

A novel minimally invasive OFM technique with orthotopic transplantation of hUC-MSCs and in vivo monitoring of liver metabolic microenvironment in liver fibrosis treatment

Background

Mesenchymal stromal cells (MSCs) transplantation showed promising therapeutic results in liver fibrosis. However, efficient cell delivery method is urgently needed and the therapeutic mechanism remains unclear. This study focused on developing a minimally invasive open-flow microperfusion (OFM) technique, which combined orthotopic transplantation of human umbilical cord-derived (hUC)-MSCs to liver and in vivo monitoring of liver microenvironment in mice with CCl₄-induced liver fibrosis.

Methods

The therapeutic potential of OFM route was evaluated by comparing OFM with intravenous (IV) injection route in terms of hUC-MSCs engraftment at the fibrosis liver, liver histopathological features, liver function and fibrotic markers expression after hUC-MSCs administration. OFM was also applied to sample liver interstitial fluid in vivo, and subsequent metabolomic analysis was performed to investigate metabolic changes in liver microenvironment.

Results

Compared with IV route, OFM route caused more hUC-MSCs accumulation in the liver and was more effective in improving the remodeling of liver structure and reducing collagen deposition in fibrotic liver. OFM transplantation of hUC-MSCs reduced blood ALT, AST, ALP and TBIL levels and increased ALB levels, to a greater extent than IV route. And OFM route appeared to have a more pronounced effect on ameliorating the CCl₄-induced up-regulation of the fibrotic markers, such as α-SMA, collagen I and TGF-β. In vivo monitoring of liver microenvironment demonstrated the metabolic perturbations induced by pathological condition and treatment intervention. Two metabolites and eight metabolic pathways, which were most likely to be associated with the liver fibrosis progression, were regulated by hUC-MSCs administration.

Conclusion

The results demonstrated that the novel OFM technique would be useful for hUC-MSCs transplantation in liver fibrosis treatment and for monitoring of the liver metabolic microenvironment to explore the underlying therapeutic mechanisms.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02599-w.

Is insulin intoxication still the perfect crime? Analysis and interpretation of postmortem insulin: review and perspectives in forensic toxicology

Insulin is an anabolic hormone essential to glucose homeostasis. Insulin therapy, comprising human insulin (HI) or biosynthetic analogs, is critical for the management of type-1 diabetes and many of type-2 diabetes. However, medication error including non-adapted dose and confusion of insulin type, and misuse, such as massive self-administration or with criminal intent, can have lethal consequences. The aim of this paper is to review the state of knowledge of insulin analysis in biological samples and of the interpretation of insulin concentrations in the situation of insulin-related death investigations. Analytic aspects are considered, as quantification can be strongly impacted by methodology. Immunoanalysis, the historical technique, has a prominent role due to its sensitivity and ease of implementation. Recently, liquid chromatography coupled to mass spectrometry has provided indispensable selectivity in forensic contexts, distinguishing HI, analogs, and degradation products. We review the numerous antemortem (dose, associated pathology, injection-to-death interval, etc.) and postmortem parameters (in corpore degradation, in vitro degradation related to hemolysis, etc.) involved in the interpretation of insulin concentration. The interest and limitations of various alternative matrices providing a valuable complement to blood analysis are discussed. Vitreous humor is one of the most interesting, but the low diffusion of insulin in this matrix entails very low concentrations. Injection site analysis is relevant for identifying which type of insulin was administered. Muscle and renal cortex are matrices of particular interest, although additional studies are required. A table containing most case reports of fatal insulin poisoning published, with analytical data, completes this review. A logic diagram is proposed to highlight analytical issues and the main parameters to be considered for the interpretation of blood concentrations. Finally, it remains a challenge to provide reliable biological data and solid interpretation in the context of death related to insulin overdose. However, the progress of analytical tools is making the "perfect crime" ever more difficult to commit.

Comparative effects of different whole grains and brans on blood lipid: a network meta-analysis

Purpose

The comparative effects of different whole grains and brans on blood lipid are still not totally elucidated. We aimed to estimate and rank the effects of different whole grains and brans on the control of blood lipid.

Methods

We performed a strategic literature search of PubMed, EMBASE and the Cochrane Library for relevant trials. Both pairwise meta-analyses and network meta-analyses were conducted to compare and rank the intervention strategies of whole grains and brans for the control of total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), and triglycerides (TG).

Results

Fifty-five eligible trials with a total of 3900 participants were included. Cumulative ranking analyses showed that oat bran was the most effective intervention strategy for TC and LDL-C improvements, with significant decreases of − 0.35 mmol/L (95% CI − 0.47, − 0.23 mmol/L) and − 0.32 mmol/L (95% CI − 0.44, − 0.19 mmol/L) in TC and LDL-C compared with control, respectively. In comparison with control, oat was associated with significant reductions in TC by − 0.26 mmol/L (95% CI − 0.36, − 0.15 mmol/L) and LDL-C by − 0.17 mmol/L (95% CI − 0.28, − 0.07 mmol/L), which was ranked as the second best treatment. Barley, brown rice, wheat and wheat bran were shown to be ineffective in improving blood lipid compared with control.

Conclusions

This network meta-analysis suggests that oat bran and oat are ranked higher than any other treatments for the regulations of TC and LDL-C, indicating that increasing oat sources of whole grain may be recommended for lipid control.

Electronic supplementary material

The online version of this article (10.1007/s00394-018-1827-6) contains supplementary material, which is available to authorized users.

Quantification of Basal Insulin Peglispro and Human Insulin in Adipose Tissue Interstitial Fluid by Open-Flow Microperfusion

BACKGROUND

Restoration of the physiologic hepatic-to-peripheral insulin gradient may be achieved by either portal vein administration or altering insulin structure to increase hepatic specificity or restrict peripheral access. Basal insulin peglispro (BIL) is a novel, PEGylated basal insulin with a flat pharmacokinetic and glucodynamic profile and altered hepatic-to-peripheral action gradient. We hypothesized reduced BIL exposure in peripheral tissues explains the latter, and in this study assessed the adipose tissue interstitial fluid (ISF) concentrations of BIL compared with human insulin (HI).

METHODS

A euglycemic glucose clamp was performed in patients with type 1 diabetes during continuous intravenous (IV) infusion of BIL or HI, while the adipose ISF insulin concentrations were determined using open-flow microperfusion (OFM). The ratio of adipose ISF-to-serum concentrations and the absolute steady-state adipose ISF concentrations were assessed using a dynamic no-net-flux technique with subsequent regression analysis.

RESULTS

Steady-state BIL concentrations in adipose tissue ISF were achieved by ∼16 h after IV infusion. Median time to reach steady-state glucose infusion rate across doses ranged between 8 and 22 h. The average serum concentrations (coefficient of variation %) of BIL and HI were 11,200 pmol/L (23%) and 425 pmol/L (15%), respectively. The ISF-to-serum concentration ratios were 10.2% for BIL and 22.9% for HI.

CONCLUSIONS

This study indicates feasibility of OFM to measure BIL in ISF. The observed low ISF-to-serum concentration ratio of BIL is consistent with its previously demonstrated reduced peripheral action.