Lacrimal gland organoids: A systematic review on development, characterization, molecular profiling and translational...

Organoids are mini-organs engineered to mimic the native tissue's organization, cellular structure, and function. Lacrimal gland organoids are considered a potential treatment for patients with dry eye, but the gland's complex heterogeneity has been difficult to replicate. This systematic review summarizes methods for creating lacrimal gland organoids, their characterization, and potential applications. Data collected included organoid source, composition of expansion or differentiation media, biomarkers, gene expression, responses to stimulants, and effects in animal models. The sources of lacrimal gland organoids were human induced pluripotent stem (hiPS) cell lines (n = 2) and tissue biopsies from humans, mice, or pigs (n = 5). Tissue-derived organoids from mice grew for 40 passages, while those from human biopsies lasted up to 20 passages. There is a need to optimize the culture protocol to preserve cell composition and support long-term growth. The organoids expressed epithelial markers (KRT5, KRT13, AQP), mesenchymal markers (Vimentin and α-SMA), and developmental markers (PAX6, TP63, and OCT3/4), though cellular proportions varied between studies. Stimulation studies showed increased calcium influx and β-glucosaminidase activity, indicating secretory capacity. RNA sequencing revealed unique gene expression patterns associated with stemness and functional maturity, including tear proteins and markers of ductal and myoepithelial cells. PAX6 knockout studies confirmed PAX6's essential role in organoid growth. Published studies lack data on epithelial polarity, the coexistence of ductal and acinar cells within organoids, and the in vivo secretory function of organoids. Transplanted organoids into animal models of dry eye disease (two immunosuppressed and two naïve) remained viable for 8 weeks and expressed tear-related markers (AQP5, KRT14, PAX6), although there was no data on tear film or ocular surface changes. Future research could explore the effects of transplantation on the ocular surface and host immune responses.