Biodegradable polymer possesses significant potential for applications in different fields, since flexibility gives rise to materials with great physical and mechanical property diversity. The poly-caprolactone (PCL) and chitosan derivatives (CS) have the ability to form scaffolds, which adhere to the surface of mesoporous silica nanoparticles (MSNs) and its porous networks. The novel characteristics of the developed PCL/MSNs and CS/MSNs, such as very low in vivo degradation rate, ordered pore network, uniform and tunable size and shape of the particles, high pore volume and surface area, non-toxicity, and biocompatibility, among others, are responsible for its favorable gene delivery device and makes this conjugation a very good biomaterial for this application. In the present study, we investigated the synthesis of silica nanoparticles MCM-41 covalently grafted with PCL and CS and their use as a potential small interfering RNA (siRNA) carrier. The physical–chemical and morphological characterizations, as well as the applicability of functionalized MSNs as platforms for gene delivery, were assessed. Our results confirmed that MSNs that were successfully functionalized with PCL and CS kept their typical morphology and pore arrangement. Furthermore, their surface modification was successfully held. In vitro biocompatibility and cytotoxicity assays suggest the ability of MSNs to support passive uptake and indicated the potential of this material as a gene delivery system for cervical cancer cells (HeLa).

Introduction: Multipotent mesenchymal stromal cells (MSCs) have gained considerable interest because of their potential use in the treatment of a variety of diseases and injuries. Although remarkable advancements have been made in clinical studies, substantial concerns still regard the safety of MSCs. Some evidence suggests that MSCs can spontaneously generate a population of cells with tumorigenic potential. Thus, studying the molecular mechanisms that control the proliferation of MSCs may be a necessary step toward the development of strategies for safe clinical practice. Ca²⁺ is a second messenger that mediates a wide range of cellular responses, including the regulation of cell proliferation, but little is known about its function in MSCs. The aim of this study was to investigate the effects of targeted Ca²⁺ buffering on MSCs proliferation in vitro. Methods: Here, we used an adenoviral (Ad) vector encoding the Ca²⁺ chelator protein parvalbumin (PV) fused to a nuclear exclusion signal (NES) and the Discosoma red fluorescent protein (DsRed) to investigate the function of cytoplasmic Ca²⁺ signals on MSC proliferation. Confocal microscopy was used to demonstrate that PV-NES-DsRed was expressed in the cytoplasm. Ca²⁺ signaling was monitored by using Fluo-4-AM. Fluorescence-activated cell sorting (FACS) analysis of cells that were stained with propidium iodide was used as a quantitative measure of cell death. The mitotic index was assessed by immunofluorescence, and the expression of cyclins was examined with Western blot. Results: Our results show that the Ad-PV-NES-DsRed fusion protein decreased serum-induced Ca²⁺ signaling and blocked the proliferation of rat adipose-derived MSCs (AT-MSCs) in prophase. FACS analysis revealed that Ad-PV-NES-DsRed did not induce cell death in AT-MSCs. Furthermore, Western blot analysis demonstrated that Ad-PV-NES-DsRed reduced extracellular signal-regulated kinase (Erk1/2) phosphorylation and cyclin B1 expression. Buffering cytosolic Ca²⁺ did not alter the expression of cyclins A/D1/D2/D3/E and E2. Conclusions: Our results show that cytoplasmic Ca²⁺ signals are important for AT-MSCs progression beyond prophase because of their effects on Erk phosphorylation and cyclin B1 expression.