Non-invasive cell tracking of SPIO labeled cells in an intrinsic regenerative environment: The axolotl limb

Influence of SPIO labelling on the function of BMSCs in chemokine receptors expression and chemotaxis

Bone marrow-derived mesenchymal stem cells (BMSCs) are increasingly being used in bone marrow transplantation (BMT) to enable homing of the allogeneic hematopoietic stem cells and suppress acute graft versus host disease (aGVHD). The aim of this study was to optimize the labelling of BMSCs with superparamagnetic iron oxide particles (SPIOs), and evaluate the impact of the SPIOs on the biological characteristics, gene expression profile and chemotaxis function of the BMSCs. The viability and proliferation rates of the SPIO-labeled BMSCs were analyzed by trypan blue staining and CCK-8 assay respectively, and the chemotaxis function was evaluated by the transwell assay. The expression levels of chemokine receptors were measured by RT-PCR and flow cytometry. The SPIOs had no effect on the viability of the BMSCs regardless of the labelling concentration and culture duration. The labelling rate of the cells was higher when cultured for 48 h with the SPIOs. Furthermore, cells labeled with 25 µg/ml SPIOs for 48 h had the highest proliferation rates, along with increased expression of chemokine receptor genes and proteins. However, there was no significant difference between the chemotaxis function of the labeled and unlabeled BMSCs. To summarize, labelling BMSCs with 25 µg/ml SPIOs for 48h did not affect their biological characteristics and chemotaxis function, which can be of significance for in vivo applications.

A Dual-Mode Imaging Nanoparticle Probe Targeting PD-L1 for Triple-Negative Breast Cancer

Chemotherapy has remained the mainstay of treatment of triple-negative breast cancer; however, it is significantly limited by the associated side effects. PD-1/PD-L1 immune checkpoint inhibition therapy (ICI) has been a breakthrough for this patient population in recent years. PD-L1 expression is crucial in immunotherapy since it is a major predictor of PD-1/PD-L1 antibody response, emphasizing the significance of monitoring PD-L1 expression. Nonetheless, it is hard to assess the expression of PD-L1 before surgery, which has highlighted the urgency for a precise and noninvasive approach. Herein, we prepared a dual-mode imaging nanoparticle probe to detect PD-L1. The particle size, zeta potential, biocompatibility, and imaging ability of NPs were characterized. The synthesized NPs showed slight cytotoxicity and good T2 relaxivity. The targeted NPs accumulated more in 4T1 cells than nontargeted NPs in vitro. The in vivo experiment further demonstrated the distribution of targeted NPs in tumor tissues, with changes in NIRF and MR signals observed. Our study indicated that SPIO-aPD-L1-Cy5.5 NPs can be used to monitor PD-L1 expression in breast cancer as NIRF/MR contrast agents.

Nanotechnology-Assisted Cell Tracking

The usefulness of nanoparticles (NPs) in the diagnostic and/or therapeutic sector is derived from their aptitude for navigating intra- and extracellular barriers successfully and to be spatiotemporally targeted. In this context, the optimization of NP delivery platforms is technologically related to the exploitation of the mechanisms involved in the NP–cell interaction. This review provides a detailed overview of the available technologies focusing on cell–NP interaction/detection by describing their applications in the fields of cancer and regenerative medicine. Specifically, a literature survey has been performed to analyze the key nanocarrier-impacting elements, such as NP typology and functionalization, the ability to tune cell interaction mechanisms under in vitro and in vivo conditions by framing, and at the same time, the imaging devices supporting NP delivery assessment, and consideration of their specificity and sensitivity. Although the large amount of literature information on the designs and applications of cell membrane-coated NPs has reached the extent at which it could be considered a mature branch of nanomedicine ready to be translated to the clinic, the technology applied to the biomimetic functionalization strategy of the design of NPs for directing cell labelling and intracellular retention appears less advanced. These approaches, if properly scaled up, will present diverse biomedical applications and make a positive impact on human health.

Synthesis of SPIO Nanoparticles and the Subsequent Applications in Stem Cell Labeling for Parkinson's Disease

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the midbrain, and the stem cell transplantation method provides a promising strategy for the treatment. In these studies, tracking the biological behaviors of the transplanted cells in vivo is essential for a basic understanding of stem cell function and evaluation of clinical effectiveness. In the present study, we developed a novel ultrasmall superparamagnetic iron oxide nanoparticles coating with the polyacrylic acid (PAA) and methoxypolyethylene glycol amine (PEG) by thermal decomposition method and a two-step modification. The USPIO-PAA/PEG NPs have a uniform diameter of 10.07 ± 0.55 nm and proper absorption peak of the corresponding ligands, as showed by TEM and FTIR. MTT showed that the survival of cells incubated with USPIO-PAA/PEG NPs remained above 96%. The synthesized USPIO-PAA/PEG had a good relaxation rate of 84.65 s^-1 Mm^-1, indicating that they could be efficiently uptake and traced by MRI. Furthermore, the primary human adipose-derived stem cells (HADSCs) were characterized, labeled with USPIO-PAA/PEG and transplanted into the striatum of 6-hydroxydopamine (6-OHDA)-induced PD rat models. The labeled cells could be traced by MRI for up to 3 weeks after the transplantation surgery; moreover, transplantation with the labeled HADSCs significantly attenuated apomorphine-induced rotations in PD models and increased the number of the dopaminergic neurons in the substania nigra. Overall, the development of USPIO-PAA/PEG NPs provides a promising tool for in vivo tracing technique of cell therapy and identifies a novel strategy to track stem cells with therapeutic potential in PD.