Retinal organoids on-a-chip: a micro-millifluidic bioreactor for long-term organoid maintenance

Yuntian Xue; Magdalene J. Seiler; William C. Tang; Jasmine Y. Wang; Jeffrey Delgado; Bryce T. McLelland; Gabriel Nistor; Hans S. Keirstead; Andrew W. Browne

doi:10.1039/D1LC00011J

Retinal organoids on-a-chip: a micro-millifluidic bioreactor for long-term organoid maintenance†

Yuntian Xue,

^a Magdalene J. Seiler,

^bcde William C. Tang,

^a Jasmine Y. Wang,^f Jeffrey Delgado,^c Bryce T. McLelland,^g Gabriel Nistor,^g Hans S. Keirstead^g and Andrew W. Browne

*^adh

Author affiliations

* Corresponding authors

^a Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
E-mail: abrowne1@hs.uci.edu

^b Physical Medicine & Rehabilitation, University of California, Irvine, Irvine, CA, USA

^c Stem Cell Research Center, University of California, Irvine, Irvine, CA, USA

^d Gavin Herbert Eye Institute Department of Ophthalmology, University of California, Irvine, Irvine, CA, USA

^e Anatomy & Neurobiology, University of California, Irvine, Irvine, CA, USA

^f School of Biological Sciences, University of California, Irvine, Irvine, CA, USA

^g AIVITA Biomedical, Irvine, CA, USA

^h Institute for Clinical and Translational Science, University of California, Irvine, Irvine, CA, USA

Abstract

Retinal degeneration is a leading cause of vision impairment and blindness worldwide and medical care for advanced disease does not exist. Stem cell-derived retinal organoids (RtOgs) became an emerging tool for tissue replacement therapy. However, existing RtOg production methods are highly heterogeneous. Controlled and predictable methodology and tools are needed to standardize RtOg production and maintenance. In this study, we designed a shear stress-free micro-millifluidic bioreactor for nearly labor-free retinal organoid maintenance. We used a stereolithography (SLA) 3D printer to fabricate a mold from which Polydimethylsiloxane (PDMS) was cast. We optimized the chip design using in silico simulations and in vitro evaluation to optimize mass transfer efficiency and concentration uniformity in each culture chamber. We successfully cultured RtOgs at three different differentiation stages (day 41, 88, and 128) on an optimized bioreactor chip for more than 1 month. We used different quantitative and qualitative techniques to fully characterize the RtOgs produced by static dish culture and bioreactor culture methods. By analyzing the results from phase contrast microscopy, single-cell RNA sequencing (scRNA seq), quantitative polymerase chain reaction (qPCR), immunohistology, and electron microscopy, we found that bioreactor-cultured RtOgs developed cell types and morphology comparable to static cultured ones and exhibited similar retinal genes expression levels. We also evaluated the metabolic activity of RtOgs in both groups using fluorescence lifetime imaging (FLIM), and found that the outer surface region of bioreactor cultured RtOgs had a comparable free/bound NADH ratio and overall lower long lifetime species (LLS) ratio than static cultured RtOgs during imaging. To summarize, we validated an automated micro-millifluidic device with significantly reduced shear stress to produce RtOgs of comparable quality to those maintained in conventional static culture.

Lab on a Chip

Retinal organoids on-a-chip: a micro-millifluidic bioreactor for long-term organoid maintenance†

Abstract

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Retinal organoids on-a-chip: a micro-millifluidic bioreactor for long-term organoid maintenance

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