The aim of this study was an in vitro evaluation and comparison of the cytotoxic effects of free nisin and nisin-loaded PLA-PEG-PLA nanoparticles on gastrointestinal (AGS and KYSE-30), hepatic (HepG2), and blood (K562) cancer cell lines. To create this novel anti-cancer drug delivery system, the nanoparticles were synthesized and then loaded with nisin. Subsequently, their biocompatibility, ability to enter cells, and physicochemical properties, including formation, size, and shape, were studied using hemolysis, fluorescein isothiocyanate (FITC), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and scanning electron microscopy (SEM), respectively. Then, its loading efficiency and release kinetics were examined to assess the potential impact of this formulation for the nanoparticle carrier candidacy. The cytotoxicities of nisin and nisin-loaded nanoparticles were evaluated by using the MTT and Neutral Red (NR) uptake assays. Detections of the apoptotic cells were done via Ethidium Bromide (EB)/Acridine Orange (AO) staining. The FTIR spectra, SEM images, and DLS graph confirmed the formations of the nanoparticles and nisin-loaded nanoparticles with spherical, distinct, and smooth surfaces and average sizes of 100 and 200 nm, respectively. The loading efficiency of the latter nanoparticles was about 85-90%. The hemolysis test represented their non-cytotoxicities and the FITC images indicated their entrance inside the cells. An increase in the percentage of apoptotic cells was observed through EB/AO staining. These results demonstrated that nisin had a cytotoxic effect on AGS, KYSE-30, HepG2, and K562 cancer cell lines, while the cytotoxicity of nisin-loaded nanoparticles was more than that of the free nisin.

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Tissue engineering is used for regenerating bioartificial tissues using suitable cells and biocompatible scaffold materials. The present study aims to prepare poly (lactic acid) (PLA) nanoparticles as an extracellular matrix to use in bone tissue engineering. For this purpose, the stem cells originating from the human umbilical cord were extracted and their adhesion, growth, and osteoblastic differentiation on the PLA scaffold were studied. First, the PLA nano-scaffold was fabricated by solvent casting/salt leaching method, and then its properties including formation, surface properties, porosity, pore size, pore distribution, biocompatibility, and biodegradability were evaluated. After extracting mesenchymal stem cells (MSCs) from the umbilical cord of human embryos, they were cultured on the scaffold, and then flow cytometry was used to prove their stemness. The morphological properties of the scaffold and differentiated cells attached to it were investigated using scanning electron microscopy (SEM), Alizarin red, and Von kossa staining. The results of SEM and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tests for evaluating its biocompatibility showed that this scaffold has suitable surface properties for cell growth and proliferation. The result of flow cytometry demonstrated more than 90% expression of CD105 and CD90 markers (MSCs markers) and no expression of CD45 (hematopoietic marker) on the cell's surface. The images of Alizarin red staining, Von kossa staining, and SEM confirmed calcium deposition on the scaffold containing cells differentiated to osteoblasts. This study showed that MSCs can adhere, proliferate and differentiate to bone cells (osteoblasts) on PLA scaffold in vitro. Thus, additional experiments on this scaffold should be done for regenerating bone tissues in vivo.