Current treatment approaches for spinal cord injuries (SCIs) are mainly based on cellular transplantation. Induced pluripotent stem cells (iPSCs) without supply constraints and ethical concerns have emerged as a viable treatment option for repairing neurological disorders. However, the primarily limitations in the neuroregeneration field are uncontrolled cell differentiation, and low cell viability caused by the ischemic environment. The mechanical property of three-dimensional (3D) hydrogel can be easily controlled and shared similar characteristics with nerve tissue, thus promoting cell survival and controlled cell differentiation. We propose the combination of a 3D gelatin methacrylate (GelMA) hydrogel with iPSC-derived NSCs (iNSCs) to promote regeneration after SCI. In vitro, the iNSCs photoencapsulated in the 3D GelMA hydrogel survived and differentiated well, especially in lower-moduli hydrogels. More robust neurite outgrowth and more neuronal differentiation were detected in the soft hydrogel group. To further evaluate the in vivo neuronal regeneration effect of the GelMA hydrogels, a mouse spinal cord transection model was generated. We found that GelMA/iNSC implants significantly promoted functional recovery. Further histological analysis showed that the cavity areas were significantly reduced, and less collagen was deposited in the GelMA/iNSC group. Furthermore, the GelMA and iNSC combined transplantation decreased inflammation by reducing activated macrophages/microglia (CD68-positive cells). Additionally, GelMA/iNSC implantation showed striking therapeutic effects of inhibiting GFAP-positive cells and glial scar formation while simultaneously promoting axonal regeneration. Undoubtedly, use of this 3D hydrogel stem cell-loaded system is a promising therapeutic strategy for SCI repair.

This study using dyadic approach, focused on the impact of personality traits and basic human values on the synchrony and the average level of perceived friendship quality between dyads. We used the Friendship Quality Questionnaire to measure the perceived friendship quality levels of the involved parties, the 50-item IPIP version of Big Five Questionnaire to quantify the individual personality traits and a Short Swartz Values Survey to characterize different basic human values. Two aggregated measures were defined based on the score of friendship quality of each party of the friends. The level of friendship quality was defined as the sum of perceived quality of two persons involved in the friendship. The synchrony of friendship quality was defined by subtracting the perceived quality of one party from the other in the friendship. The level and the synchrony of each personality traits and each basic human value between dyads were quantified in a similar way. Several linear regressions were conducted in a two-step process to examine the correlation between personality traits and friendship quality and the correlation between basic values and friendship quality both at the dimension of general levels and synchrony. The results showed a significant positive effect of agreeableness on the level of friendship quality and a significant positive effect of agreeableness on the synchrony of friendship quality. Our findings highlight the association between personality and the perceived quality in dyadic relationships.

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