Coaxial bioprinted microfibers with mesenchymal stem cells for glioma microenvironment simulation

Due to their special anatomical and physiological features,central nervous system diseases still presented challenges,despite the fact that some advances have been made in early diagnosis and precision medicine.One of the complexities in treating tumors is the tumor microenvironment,which includes mesenchymal stem cells(MSCs)that exhibit tumor tropism and can be used for cell therapy.However,whether MSCs promote or suppress gliomas is still unclear,especially in glioma microenvironments.In this study,a coaxial microfiber was designed to mimic the tumor microenvironment and to reveal the effect of MSCs on glioma cells.The fiber shell was composed of MSCs and alginate,and the core was filled with U87 MG(glioblastoma)cells and gelatin methacrylate.This Shell-MSC/Core-U87 MG microenvironment improved the proliferation,survival,invasion,metastasis,and drug resistance of glioma cells,while simultaneously maintaining the stemness of glioma cells.In summary,coaxial extrusion bioprinted Shell-MSC/Core-U87 MG microfiber is an ideal platform for tumor and stromal cell coculture to observe tumor biological behavior in vitro.

A structure-supporting,self-healing,and high permeating hydrogel bioink for establishment of diverse homogeneous tissue-like constructs

The ready-to-use,structure-supporting hydrogel bioink can shorten the time for ink preparation,ensure cell dispersion,and maintain the preset shape/microstructure without additional assistance during printing.Meanwhile,ink with high permeability might facilitate uniform cell growth in biological constructs,which is beneficial to homogeneous tissue repair.Unfortunately,current bioinks are hard to meet these requirements simultaneously in a simple way.Here,based on the fast dynamic crosslinking of aldehyde hyaluronic acid(AHA)/N-carboxymethyl chitosan(CMC)and the slow stable crosslinking of gelatin(GEL)/4-arm poly(ethylene glycol)succinimidyl glutarate(PEG-SG),we present a time-sharing structure-supporting(TSHSP)hydrogel bioink with high permeability,containing 1%AHA,0.75%CMC,1%GEL and 0.5%PEG-SG.The TSHSP hydrogel can facilitate printing with proper viscoelastic property and self-healing behavior.By crosslinking with 4%PEG-SG for only 3 min,the integrity of the cell-laden construct can last for 21 days due to the stable internal and external GEL/PEG-SG networks,and cells manifested long-term viability and spreading morphology.Nerve-like,muscle-like,and cartilage-like in vitro constructs exhibited homogeneous cell growth and remarkable biological specificities.This work provides not only a convenient and practical bioink for tissue engineering,targeted cell therapy,but also a new direction for hydrogel bioink development.

A facile,versatile hydrogel bioink for 3D bioprinting benefits long-term subaqueous fidelity,cell viability and proliferation

Both of the long-term fidelity and cell viability of three-dimensional(3D)-bioprinted constructs are essential to precise soft tissue repair.However,the shrinking/swelling behavior of hydrogels brings about inadequate long-term fidelity of constructs,and bioinks containing excessive polymer are detrimental to cell viability.Here,we obtained a facile hydrogel by introducing 1%aldehyde hyaluronic acid(AHA)and 0.375%N-carboxymethyl chitosan(CMC),two polysaccharides with strong water absorption and water retention capacity,into classic gelatin(GEL,5%)–alginate(ALG,1%)ink.This GEL–ALG/CMC/AHA bioink possesses weak temperature dependence due to the Schiff base linkage of CMC/AHA and electrostatic interaction of CMC/ALG.We fabricated integrated constructs through traditional printing at room temperature and in vivo simulation printing at 37C.The printed cell-laden constructs can maintain subaqueous fidelity for 30 days after being reinforced by 3%calcium chloride for only 20 s.Flow cytometry results showed that the cell viability was 91.3861.55%on day 29,and the cells in the proliferation plateau at this time still maintained their dynamic renewal with a DNA replication rate of 6.0661.24%.This work provides a convenient and practical bioink option for 3D bioprinting in precise soft tissue repair.

A coaxially extruded heterogeneous core-shell fiber with Schwann cells and neural stem cells

Cellular therapies play a critical role in the treatment of spinal cord injury(SCI).Compared with cell-seeded conduits,fully cellular grafts have more similarities with autografts,and thus might result in better regeneration effects.In this study,we fabricated Schwann cell(SC)-neural stem cell(NSC)core–shell alginate hydrogel fibers in a coaxial extrusion manner.The rat SC line RSC96 and mouse NSC line NE-4C were used in this experiment.Fully cellular components were achieved in the core portion and the relative spatial positions of these two cells partially mimic the construction of nerve fibers in vivo.SCs were demonstrated to express more genes of neurotrophic factors in alginate shell.Enhanced proliferation and differentiation tendency of NSCs was observed when they were co-cultured with SCs.This model has strong potential for application in SCI repair.

A controllable gelatin-based microcarriers fabrication system for the whole procedures of MSCs amplification and tissue engineering

Biopolymer microbeads present substantial benefits for cell expansion,tissue engineering,and drug release applications.However,a fabrication system capable of producing homogeneous microspheres with high precision and controllability for cell proliferation,passaging,harvesting and downstream application is limited.Therefore,we developed a co-flow microfluidics-based system for the generation of uniform and size-controllable gelatin-based microcarriers(GMs)for mesenchymal stromal cells(MSCs)expansion and tissue engineering.Our evaluation of GMs revealed superior homogeneity and efficiency of cellular attachment,expansion and harvest,and MSCs expanded on GMs exhibited high viability while retaining differentiation multipotency.Optimization of passaging and harvesting protocols was achieved through the addition of blank GMs and treatment with collagenase,respectively.Furthermore,we demonstrated that MSC-loaded GMs were printable and could serve as building blocks for tissue regeneration scaffolds.These results suggested that our platform held promise for the fabrication of uniform GMs with downstream application of MSC culture,expansion and tissue engineering.