Regulatory RNAs,microRNA,long-non coding RNA and circular RNA roles in colorectal cancer stem cells

The properties of cancer stem cells(CSCs),such as self-renewal,drug resistance,and metastasis,have been indicated to be responsible for the poor prognosis of patients with colon cancers.The epigenetic regulatory network plays a crucial role in CSC properties.Regulatory non-coding RNA(ncRNA),including microRNAs,long noncoding RNAs,and circular RNAs,have an important influence on cell physiopathology.They modulate cells by regulating gene expression in different ways.This review discusses the basic characteristics and the physiological functions of colorectal cancer(CRC)stem cells.Elucidation of these ncRNAs will help us understand the pathological mechanism of CRC progression,and they could become a new target for cancer treatment.

Using 3D bioprinting to produce mini-brain

Recent progresses in three-dimensional （3D） bioprinting technology accelerate the coming of the era of personalized medicine. With vari- ous printing approaches and materials developed, 3D bioprinting may have a broad range of medical applications, including the fabrication of delicate tissues/organs/or the clinical use in the future or for the es- tablishment of tissues in disease models. The principal advantages of 3D bioprinting are personalized design and precise fabrication, which are of critical importance for tissue engineering. To date, several types of biomimetic tissues, such as cartilage, skin, and vascular tissues have been fabricated by 3D bioprinting （Liaw and Guvendiren, 2017）.

Self-healing hydrogel for tissue repair in the central nervous system

Neurological disorders are diseases of the central and peripheral nervous systems.These disorders include Alzheimer＇s disease,epilepsy,brain tumor,and cerebrovascular diseases（stroke,migraine and other headache disorders,multiple sclerosis,Parkinson＇s disease,and neuroinfections）.

Visualization of peripheral nerve regeneration

Peripheral nerve injuries are often caused by trauma and they may result in a partial or total loss of motor function or sensory perception. After nerve injuries, peripheral axons have the ability to regenerate and reconnect the proximal and distal ends of severed nerve axons if the nerve gap is small. For larger nerve gaps, surgical treatments are often required to repair the injured nerves.

Biomaterials and neural regeneration

Neural regeneration is a great clinical challenge in both the central nervous system(CNS)and the peripheral nervous system(PNS).Degeneration in the CNS caused by disease(such as Alzheimer's or Parkinson's diseases)or trauma(such as traumatic brain injury and spinal cord injury)often results in permanent paralysis and loss of sensation.The spontaneous neural regeneration in the CNS is generally unsuccessful,while the PNS has an intrinsic regenerative ability.However,PNS regeneration occurs over relatively short distances.Damage to the PNS results in the motor and cognitive impairment in many cases.Biomaterials in the form of scaffolds or nanoparticles for neuroprotection and neuroregeneration have attracted much attention.Nanoparticles can be fabricated using various lioids.

Changes of cell membrane fluidity for mesenchymal stem cell spheroids on biomaterial surfaces

BACKGROUND The therapeutic potential of mesenchymal stem cells(MSCs)in the form of threedimensional spheroids has been extensively demonstrated.The underlying mechanisms for the altered cellular behavior of spheroids have also been investigated.Cell membrane fluidity is a critically important physical property for the regulation of cell behavior,but it has not been studied for the spheroid-forming cells to date.AIM To explore the association between cell membrane fluidity and the morphological changes of MSC spheroids on the surface of biomaterials to elucidate the role of membrane fluidity during the spheroid-forming process of MSCs.METHODS We generated three-dimensional(3D)MSC spheroids on the surface of various culture substrates including chitosan(CS),CS-hyaluronan(CS-HA),and polyvinyl alcohol(PVA)substrates.The cell membrane fluidity and cell morphological change were examined by a time-lapse recording system as well as a highresolution 3D cellular image explorer.MSCs and normal/cancer cells were prestained with fluorescent dyes and co-cultured on the biomaterials to investigate the exchange of cell membrane during the formation of heterogeneous cellular spheroids.RESULTS We discovered that vesicle-like bubbles randomly appeared on the outer layer of MSC spheroids cultured on different biomaterial surfaces.The average diameter of the vesicle-like bubbles of MSC spheroids on CS-HA at 37℃ was approximately 10μm,smaller than that on PVA substrates(approximately 27μm).Based on time-lapse images,these unique bubbles originated from the dynamic movement of the cell membrane during spheroid formation,which indicated an increment of membrane fluidity for MSCs cultured on these substrates.Moreover,the membrane interaction in two different types of cells with similar membrane fluidity may further induce a higher level of membrane translocation during the formation of heterogeneous spheroids.CONCLUSION Changes in cell membrane fluidity may be a novel path to elucidate the complicated physiological alterations in 3D spheroid-forming cells.