Research And Application Of Biological Behavior Of Mesenchymal Stem Cells Based On Fluorescent Probe In The Second Near-Infrared Window

The biological imaging of the near infrared second window?NIR-?,1000-1700 nm?has higher spatial resolution and tissue penetration depth,and is affected by less absorption,scattering and autofluorescence,making the biological imaging in NIR-? has become a potential technical means to guide the diagnosis and treatment of diseases.At the same time,stem cells have excellent potential in the treatment of some incurable diseases.Various previous reports have focused on monitoring the biological function of transplanted stem cells in vivo or using BMSCs as a carrier to introduce anti-tumor drugs.However,there are still few reports on strategies to improve the homing tropism process of transplanted stem cells.To address these issues,this paper designed and synthesized a core-shell structured mesoporous silica-coated conjugated polymer nanoparticle as a new NIR-? probe ZS1000equipped with mesenchymal stem cells?BMSCs?as an enhanced near-infrared powerful tool for the tropism homing effect of transplanted BMSCs in NIR-? imaging.More importantly,with the help of ZS1000,we have successfully monitored and visualized the dynamic development of BMSCs experienced in several key pathological conditions and imaging-guided tumor surgery in real time.The specific research content of this article is mainly divided into the following two aspects:?1?Preparation of near-infrared two-window fluorescence imaging or therapeutic integrated diagnostic and therapeutic agents,extraction of mesenchymal stem cells,and in vivo imaging:a conjugated polymer PCPDTBT with an emission peak in the NIR-? region was synthesized by silanization as the core Porous silica crust?mSiO₂?is the intermediate layer.The polyethylene glycol?PEG?chain is the outermost CP@mSiO₂-PEG nanoparticles.The highly grafted PEG chain has good water solubility and biocompatibility.The synthesized CP@mSiO₂-PEG has a uniform spherical structure,uniform pores distributed on the surface,and good monodispersity.The particle size of the nanoparticles is also distributed between 30 and 40 nm.By measuring the fluorescence spectrum of nanoparticles in the near-infrared region,there is a strong fluorescence signal,and the tail of fluorescence is up to 1500 nm.This ideal NIR-? probe ZS1000 has good optical properties and biocompatibility.It is proved by experiments that loading BMSCs with ZS1000 will induce hypoxia of BMSCs,and the expression of BMSC CXCR4 is enhanced after BMSCs is labeled with ZS1000.With the help of ZS1000,real-time monitoring and visualization of the dynamic development of BMSCs experienced in imaging-guided tumor surgery.In the presence of the new NIR-? probe ZS1000,the homing effect of the BMSCs can be accelerated.The BMSCs loaded with ZS1000accumulates in the tumor area and the BMSCs marked with Ag₂S does not clearly outline the tumor.The experiment proves that the tumor is completely removed.Reduce tumor recurrence rate and mortality.It shows that this imaging strategy based on the new NIR-? probe is more advantageous than traditional methods in guiding surgery.?2?Stem cell therapy has important application prospects for bone repair,cartilage defect regeneration,skin wound healing,lymphatic disease treatment and liver injury treatment.In this chapter,we use the new NIR-? ZS1000 fluorescent probe developed in the previous chapter to use BMSCs as a biological carrier.Because of its inherent characteristics,it may induce hypoxic status and prove that the development of NIR-? nanoprobes has homing stem cells to target positions Point tracking significantly contributes.By realizing more accurate real-time monitoring of injured or defective tissues?including liver,bone,cartilage,skin and lymphatic system?,which confirmed the unique ideal characteristics of ZS1000 to accelerate the directional effect of BMSCs and accelerate the imaging of near infrared nanoprobe Combined with BMSCs multifunctional treatment to enhance stem cell therapy.while,BMSCs labeled with Ag₂S cannot achieve more accurate monitoring of injured or defective tissues?including liver,bone,cartilage,skin,and lymphatic system?and tracking of stem cell homing to target sites under the same conditions.These experiments prove that the new NIR-? probe loaded in BMSC is a powerful tool for enhancing the tropism or homing effect of BMSCs transplanted in NIR-? imaging,and has excellent application prospects for repair and reconstruction of damaged tissues.