The Regulation Of Hydroxyapatite Nanomaterials On The Differentiation Of Stem Cells

As a common bone tissue engineering material,hydroxyapatite(HAp)has excellent biocompatibility.As reported,HAp can regulate the differentiation of mesenchymal stem cells(MSCs)towards osteogenesis.The regulation of HAp on stem cell differentiation mainly focuses on adding HAp to culture system and analyzing the change of stem cell population differentiation,as well as the obtained signal comes from the collective effect formed by population expression,which proves the regulation of HAp on stem cell differentiation to a certain extent.However,during cell change process,the exosomes formed the intercellular communication,which will have an effect on other cell states.Thus,there is no way to avoid the regulation of intercellular communication on stem cell fate based on cell population,and further explore the regulation of HAp on stem cell fate.In fact,this difficulty can be avoided through the traditional single-cell level research techniques,but cell biology experiments are multi-factorial regulation,the sample size determines the reliability,so a large number of single-cell level stem cell differentiation research is necessary.Calcium ion(Ca2+)is an important ion in the regulation of cell fate.In addition to related studies on the regulation of osteoblastic differentiation,its regulatory effect on other stem cells has gradually attracted attention.HAp is rich in calcium and phosphorus,and nanometer HAp has high biological activity.Therefore,expanding the application of HAp nanomaterials in the regulation of stem cell fate,is an important content to discuss the regulation mechanism of stem cell differentiation and to develop stem cell therapy-related materials.The paper mainly carries out the following research:(1)HAp nanorods were prepared by hydrothermal method.The effect of HAp nanorods on osteogenic differentiation of human adipose mesenchymal stem cells(hADSCs)was explored at the cell population level.Furthermore,we co-designed the culture and detection chip for HAp nanorods regulating the osteogenic differentiation of hADSCs at the single-cell level based on the method of real-time detection of secreted proteins,which demonstrated the enhancing effect of HAp nanorods on the osteogenic differentiation of hADSCs at the single-cell level.It was found that HAp nanorods can initiate and promote osteogenic differentiation of hADSCs even at the single-cell level when cell-cell interaction is limited,as well as thousands of parallel experiments were carried out.(2)One-dimensional(1D)HAp nanomaterials with similar diameters and different lengths were synthesized by one-step hydrothermal reaction.A series of obtained HAp nanomaterials with good crystallinity were verified by means of X-ray diffraction(XRD),infrared spectroscopy(IR),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).It is a typical HAp structure,the surface groups are consistent and there are abundant hydroxyl groups and phosphoric acid groups.The uniform morphology and good dispersity can fully meet the requirements of cell biology experiment.The effects of 1D HAp nanomaterials with different morphologies on the fate of mouse neural stem cells(mNSCs)were studied.The results showed that 1D HAp with different morphologies could promote the differentiation of mNSCs to neurons,but the effect on the differentiation of mNSCs was different.Actually,HAp long nanowires only had a weak regulatory effect on the fate of mNSCs,while HAp short nanorods,long nanorods and short nanowires had a strong regulatory effect on the fate of mNSCs.It is suggested that HAp short nanorods,long nanorods and short nanowires can be completely or partially endocytosis by cells,which is conducive to ion release and ion induction effect,while long nanowires cannot.At the same time,the long nanowires also hindered the dispersion and cell adhesion of the nanomaterials.HAp short nanowires are similar in length to cell synapses,which can help to guide the growth and extension of cell axons,showing the strongest properties of promoting neuronal differentiation.Therefore,the synergistic effect of Ca2+ and nano-morphology induced mechanical signals is the reason why HAp short nanowires can strongly accelerate the differentiation of mNSCs into neurons in a short period of time.In summary,HAp nanomaterials with different morphologies were prepared by one-step hydrothermal reaction method.Combined with microfluidic single-cell chip,the regulation of HAp nanorods at single-cell level on the fate of hADSCs and the regulation effect of 1D HAp nanomaterials on the fate of mNSCs were explored,extending the application scope of HAp from bone tissue engineering to nerve tissue engineering.