Baker, M. B. | bioRxiv Science

bioRxiv2021

Soft, dynamic hydrogel confinement improves kidney organoid lumen morphology and reduces epithelial-mesenchymal transition in culture

Pluripotent stem cell-derived kidney organoids offer a promising solution to renal failure, yet current organoid protocols often lead to off-target cells and phenotypic alterations, preventing maturity. Here, we created various dynamic hydrogel architectures, conferring a controlled and biomimetic environment for organoid encapsulation. We investigated how hydrogel stiffness and stress relaxation affect renal phenotype and undesired fibrotic markers. We observed stiff hydrogel encapsulation led to an absence of certain renal cell types and signs of an epithelial- mesenchymal transition (EMT), whereas encapsulation in soft-stress-relaxing hydrogels led to all major renal segments, fewer fibrosis/EMT associated proteins, apical proximal tubule enrichment, and primary cilia formation, representing a significant improvement over current approaches to culture kidney organoids. Our findings show that engineering hydrogel mechanics and dynamics has a decided benefit for organoid culture. These structure-property- function relationships can enable rational design of materials, bringing us closer to functional engraftments and disease-modelling applications.

bioengineering↗

bioRxiv2020

Thiol-ene cross-linked alginate hydrogel encapsulation modulates the extracellular matrix of kidney organoids by reducing abnormal type 1a1 collagen deposition

Differentiated kidney organoids from induced pluripotent stem cells hold promise as a treatment for patients with kidney diseases. Before these organoids can be translated to the clinic, shortcomings regarding their cellular, extracellular compositions and developmental plateau needs to be overcome. We performed a proteomic analysis on kidney organoids cultured for a prolonged culture time and we found a specific change in the extracellular matrix composition with increased expression of types 1a1, 2 and 6a1 collagen. Such an excessive accumulation of specific collagen types is a hallmark of renal fibrosis that causes a life-threatening pathological condition by compromising key functions of the human kidney. Here we hypothesized the need for a three-dimensional environment to grow the kidney organoids, which could better mimic the in vivo surroundings of the developing kidney than standard culture on a transwell filter. Encapsulating organoids for four days in a soft, thiol-ene cross-linked alginate hydrogel resulted in decreased type 1a1 collagen expression. Furthermore, the encapsulation did not result in any changes of organoid structural morphology. Using a biomaterial to modulate collagen expression allows for a prolonged kidney organoid culture in vitro and a reduction of abnormal type 1a1 collagen expression bringing kidney organoids closer to clinical application. HIGHLIGHTSO_LIProlonging kidney organoid culture results in a developmental plateau instead of improved in vitro maturation. C_LIO_LIProteomic analyses point to an increased expression of specific collagen subtypes associated with renal fibrosis. C_LIO_LIEncapsulating kidney organoids using a soft thiol-ene cross-linked alginate hydrogel reduces collagen type 1a1 and SMA deposition. C_LI

bioengineering↗