Injectable Therapeutic Organoids Using Sacrificial Hydrogels

Abstract

Organoids are becoming widespread in drug-screening technologies but have been used sparingly for cell therapy as current approaches for producing selforganized cell clusters lack scalability or reproducibility in size and cellular organization. We introduce a method of using hydrogels as sacrificial scaffolds, which allow cells to form self-organized clusters followed by gentle release, resulting in highly reproducible multicellular structures on a large scale. We demonstrated this strategy for endothelial cells and mesenchymal stem cells to self-organize into blood-vessel units, which were injected into mice, and rapidly formed perfusing vasculature. Moreover, in a mouse model of peripheral artery disease, intramuscular injections of blood-vessel units resulted in rapid restoration of vascular perfusion within seven days. As cell therapy transforms into a new class of therapeutic modality, this simple method-by making use of the dynamic nature of hydrogels-could offer high yields of self-organized multicellular aggregates with reproducible sizes and cellular architectures.

Towards organoid culture without Matrigel

“…In addition to organoids grown in naturally-derived proteins, several laboratories have grown a wide range of organoids in polysaccharides such as alginate or alginate-chitosan mixtures. Organoid types grown in alginate include human lung 99 , 100 , human brain 101 , murine intestinal 102 , human intestinal 102 , 103 , human pancreatic 104 , and human and murine vascular 105 . Capeling and colleagues grew HIOs on an alginate substrate and found that differentiation of human pluripotent cells into HIOs could be supported without the alginate providing chemical cues to the cells.…”

“…The authors hypothesized that cells create their own niche within the alginate hydrogel by secreting basement membrane proteins and forming mesenchyme, allowing cellular survival and differentiation into HIOs 103 . Rossen and colleagues demonstrated the development of murine and human vascular organoids in a non-functionalized alginate setting 105 . Alginate has a number of advantages that make it attractive as a material for further study; it is inexpensive, relatively easy to modify and functionalize, biocompatible, and has been used in a wide range of biological and materials applications 106 – 108 .…”

“…While the backbone materials of synthetic hydrogels are cheap and can be produced on an industrial scale, functionalization of these materials with precisely-placed, custom-made peptides significantly increases cost and requires expertise in materials science, making these materials less attractive to cell biology labs. There have been a number of studies showing that organoids can be grown on unmodified surfaces such as alginate, but this requires more research 103 , 105 , 110 , 175 , 183 . Further, synthetic hydrogels may degrade into cytotoxic by-products 184 or require cytotoxic initiators 185 , limiting the types of polymers that can be used in cell culture 186 .…”

Islet organoid as a promising model for diabetes

“…The influence of xenogeneic contamination and undefined ingredients on the cellular microenvironment and organoid morphology or function remains unclear. To render the induced products amenable to transplantation, organoids need to be fully purified by enzymatic digestion to remove scaffolds (Wang et al, 2017 ; Rossen et al, 2020 ). Another strategy is culture of the organoids in medical grade scaffolds, either derived from decellularized porcine tissues (Giobbe et al, 2019 ) or synthesized with defined components.…”

The Translational Application of Hydrogel for Organoid Technology: Challenges and Future Perspectives

“…Last but not least, sacrificial or degradable hydrogels were utilized by Rossen et al to combine cellular clusters with satisfactory reproducibility or scalability, [ 117 ] indicating the importance of hydrogel structure designs. Notably, due to the advantage of 3D unique structure, organoid technology might also be useful for immunology research.…”