From Tuneable Peptide Self-Assembly to Biologically Instructive Materials

Multifunctional biomaterials which exhibit well-defined physicochemical properties and encode spatiotemporally controlled biological signals are emerging as next generation advanced cell culture systems. One of the most biologically potent and interesting molecules are self-assembling peptides. Minimalistic approaches can be used to find short peptide sequences with tendency for aggregation towards particular structures.¹ Indeed, by the choice of primary peptide sequence, functional materials with defined nanostructure, mechanics and biological responsiveness can be designed.² So-called β-sheet forming peptides are very attractive for the design of biomaterials, in particular hydrogels, emulgels/emulsions and microgels.^3-5 These materials are highly hydrated and built from amphiphilic or polymeric nanofibres that can mimic extracellular matrix (ECM),⁶ and have been shown to be biocompatible and tailorable in terms of their physicochemical and biological properties.<br/>In this presentation we uncover the link between basic molecular interactions driving self-assembly of functional peptide-based biomaterials (hydrogels, emulgels)^{3, 5}and demonstrate their capabilities as platforms for a range of biomedical applications spanning tissue engineering, controlled drug delivery, controlled organoids growth as well as shed light on their new immunopharmacological potential when formulated with hyularonic acid. Chemical modifications of amino acids including edge-modifications and substitions will be discussed and their impact on generating biofunctional materials revealed.<br/>These materials were used to produce human induced pluripotent stem cell (hiPSC)-derived kidney organoids, which have prospective applications ranging from basic disease modelling to personalised medicine. We demonstrate how the self-assembling peptide hydrogels with varied mechanical properties affect kidney organoids growth and provide fully controllable and physiologically relevant 3D growth environments for differentiation of cells, critically improving organoid reproducibility and maturation, as compared to the animal-derived Matrigel matrix. The resulting organoids contained complex structures comparable to those differentiated within the animal-derived matrix. Single-cell RNA sequencing of organoids compositional analysis revealed a larger proportion of nephron cell types within Transwell-derived organoids, while organoids grown in peptide-based hydrogels were enriched for stromal-associated cell populations. Notably, differentiation within a higher stiffness matrix generated podocytes with more mature gene expression profiles. As such, tuneable peptide-based platforms are effective minimally complex microenvironments for the selected differentiation of kidney organoids with distinct subpopulation dependent on the selected stiffness.<br/><b>Acknowledgements</b><br/>The authors acknowledge support from Science Foundation Ireland (16/IA/4584 and 13/IA/1840), from the Royal Society of Chemistry (M19-6613) and from Manchester BIOGEL. J.K.W. acknowledges European Union’s Horizon 2020 (H2020-MSCA-IF-2019) research and innovation programme under the Marie Sklodowska-Curie grant agreement 893099 — ImmunoBioInks.<br/><b>References</b><br/>1. Y. Tang, S. Bera, et al., Cell Reports Physical Science, 2021, 100579.<br/>2. F. Sheehan, D. Sementa, et al., Chemical Reviews, 2021.<br/>3. J. K. Wychowaniec, R. Patel, et al., Biomacromolecules, 2020, 21, 2670-2680.<br/>4. S. Bai, C. Pappas, et al., ACS Nano, 2014, 8, 7005-7013.<br/>5. J. K. Wychowaniec, A. M. Smith, et al., Biomacromolecules, 2020, 21, 2285-2297.<br/>6. H. Geckil, F. Xu, et al., Nanomedicine, 2010, 5, 469-484.