Impacts of icodextrin on integrin-mediated wound healing of peritoneal mesothelial cells

Differential effects of biocompatible peritoneal dialysis fluids on human mesothelial and endothelial cells in 2D and 3D phenotypes

INTRODUCTION

Peritoneal dialysis (PD) is a life maintaining treatment in patients with end-stage renal disease. Its chronic application leads to peritoneal mesothelial layer denudation and fibrotic transformation along with vascular activation of inflammatory pathways. The impact of different PD fluids (PDF) on mesothelial and endothelial cell function and repair mechanisms are not comprehensively described.

MATERIALS AND METHODS

Mesothelial (MeT-5A) and endothelial cells (EA.hy926) were cultured in 1:1 ratio with cell medium and different PDF (icodextrin-based, amino acid-based, and glucose-based). Cell adhesion, cell migration, and cell proliferation in 2D and spheroid formation and collagen gel contraction assays in 3D cell cultures were performed.

RESULTS

Cell proliferation and cell-mediated gel contraction were both significantly decreased in all conditions. 3D spheroid formation was significantly reduced with icodextrin and amino acid PDF, but unchanged with glucose PDF. Adhesion was significantly increased by amino acid PDF in mesothelial cells and decreased by icodextrin and amino acid PDF in endothelial cells. Migration capacity was significantly decreased in mesothelial cells by all three PDF, while endothelial cells remained unaffected.

CONCLUSIONS

In 3D phenotypes the effects of PDF are more uniform in both mesothelial and endothelial cells, mitigating spheroid formation and gel contraction. On the contrary, effects on 2D phenotypes are more uniform in the icodextrin and amino acid PDF as opposed to glucose ones and affect mesothelial cells more variably. 2D and 3D comparative assessments of PDF effects on the main peritoneal membrane cell barriers, the mesothelial and endothelial, could provide useful translational information for PD studies.

Glucose Induces ER Stress Response-Mediated Peritoneal Mesothelial Cell Death

Peritoneal dialysis (PD) fluid, which contains a high concentration of glucose, is involved in peritoneal damage after long-term use. The mechanisms through which glucose induces damage to the mesothelium have not been clearly elucidated. Although, endoplasmic reticulum (ER) stress response is associated with several diseases, the involvement of ER stress in peritoneal damage has not yet been demonstrated. Primary-cultured rat peritoneal mesothelial cells (RPMCs) and rat PD model were used to investigate the influence of glucose on the peritoneum. Cells treated with glucose were examined for cytotoxicity, induction of apoptosis, and activation of the ER stress pathway. Glucose treatment of RPMCs induced cell death at concentrations higher than 3%. Annexin V positive, that is a feature of apoptosis, occurred in dead cells. Treatment with glucose led to the activation of protein kinase R-like ER kinase (PERK) and eukaryotic translation initiation factor-2α (eIF-2α). Glucose also induced the expression and nuclear translocation of homologous protein C/EBP. Cell death was rescued by the integrated stress response inhibitor, ISRIB, which suppresses the integrated stress response pathway, including ER stress. Glucose in PD fluid induces PERK/eIF-2α-mediated ER stress in RPMCs, resulting in apoptosis. This cellular stress may cause peritoneal damage in patients receiving PD.

Experimental evaluation of icodextrin delivery as pressurized aerosol (PIPAC): Antiadhesive and cytotoxic effects

BACKGROUND

Icodextrin (IDX) is an antiadhesive polymer that can be used as a carrier solution for intraperitoneal (IP) delivery of chemotherapeutic drugs.

METHODS

We investigated the suitability of IDX solution as a carrier of Cisplatin and Doxorubicin for delivery as pressurized intraperitoneal aerosol chemotherapy (PIPAC). We examined the sprayability of IDX, the aerosol characteristics, the stability of the molecule after aerosolization, the effects of IDX on the adhesion of MKN45 human gastric cancer cells, the synergistic effect of aerosolized IDX with Cisplatin and Doxorubicin, and the chemical stability of IDX, Cisplatin, and Doxorubicin in combination.

RESULTS

Delivery of IDX as PIPAC is feasible with no particular restrictions. The median droplet size of 35.7 μm did not change at increasing concentrations. IDX withstood the shear forces applied by the nebulizer and remained stable after aerosolization (ANOVA, p = 0.97). IDX did not impair the cytotoxic effects of Cisplatin and Doxorubicin (ns). IDX had a significant antiadhesive impact alone (p < 0.03) and in combination with Cisplatin and Doxorubicin (p < 0.02). IDX as a carrier for Cisplatin and Doxorubicin remained stable at 4 °C for three months and did not cause degradation of those two substances.

CONCLUSION

The proposed combination takes advantage of the antiadhesive properties of IDX, the cytotoxic effect of Cisplatin and Doxorubicin, and an advanced drug delivery system.

[Icodextrin: What arguments for and against its use as an osmotic agent in peritoneal dialysis]

Icodextrin is a glucose polymer derived from starch that is used as an osmotic agent in peritoneal dialysis. Its high molecular weight limits blood absorption and is useful for long dwell since there is few osmotic gradient dispersal. Its benefits are numerous: ltrafiltration optimization and better salt and water control especially in anuric patients with a high peritoneal permeability and also in case of infectious peritonitis, glucose sparing with less metabolic complications and a better preservation of peritoneal membrane, better biocompatibility. However it should not be forgotten that icodextrin has also side effects that must be known: allergies, cases of aseptic peritonitis, overintense water and salt depletion, lymphatic absorption of icodextrin and its metabolites (including maltose) with a risk of false capillary glucose rate estimation and a moderate increase in plasma osmolality. That is why it is not recommended now to use more than one daily icodextrin dwell. Nevertheless, several dialysis units use icodextrin in more than one daily dwell, especially in patients with an important ultrafiltration loss or in those in whom glucose sparing is essential. It seems to profit them with no more side effects. A large multicenter trial is in progress to test the efficacy and safety of icodextrin dwell twice a day in elder incident patients in peritoneal dialysis (DIDo). Moreover, icodextrin is also used combined with glucose in a long dwell (bimodal ultrafiltration) with encouraging results in terms of ultrafiltration and glucose sparing.

The overexpression of SOX2 affects the migration of human teratocarcinoma cell line NT2/D1

The altered expression of the SOX2 transcription factor is associated with oncogenic or tumor suppressor functions in human cancers. This factor regulates the migration and invasion of different cancer cells. In this study we investigated the effect of constitutive SOX2 overexpression on the migration and adhesion capacity of embryonal teratocarcinoma NT2/D1 cells derived from a metastasis of a human testicular germ cell tumor. We detected that increased SOX2 expression changed the speed, mode and path of cell migration, but not the adhesion ability of NT2/D1 cells. Additionally, we demonstrated that SOX2 overexpression increased the expression of the tumor suppressor protein p53 and the HDM2 oncogene. Our results contribute to the better understanding of the effect of SOX2 on the behavior of tumor cells originating from a human testicular germ cell tumor. Considering that NT2/D1 cells resemble cancer stem cells in many features, our results could contribute to the elucidation of the role of SOX2 in cancer stem cells behavior and the process of metastasis.