Complement Factor H (Y402H) polymorphism for age-related macular degeneration alters retinal lipids

bioRxiv (Cold Spring Harbor Laboratory) · 2026-01-07

Age-related macular degeneration (AMD), the leading cause of blindness in the elderly, is associated with multiple risk factors and involves death of the retinal pigment epithelium (RPE). We investigated how the Y402H polymorphism of Complement Factor H (CFH) and cigarette smoke extract (CSE), major AMD genetic and environmental risks, affect lipid metabolism in RPE differentiated from induced pluripotent stem cells (iPSC-RPE) that were derived from human donors genotyped for low-risk (LR) or high-risk (HR) CFH. Results from discovery-based (lipidomics, proteomics) and targeted (mitochondrial fatty acid oxidation (FAO)) assays found significant genotype-dependent differences under basal conditions include higher free fatty acids and cholesterol esters in HR cells. CSE induced differences in proteins regulating lipid handling, lipolysis, and inflammation. Lower FAO in HR cells was observed in multiple donors and pairs of parent/isogenic edited lines compared with LR lines. CSE induced lipid accumulation, lipid composition remodeling, and upregulation of proteins involved in lipid synthesis/hydrolysis, production of bioactive lipid mediators, and metabolism of ceramide and cholesterol. These results elucidate putative mechanisms driving pathology in RPE harboring CFH Y402H.

Rise of the new generation of mechanical heart valve prostheses: An in-depth in vitro study

Journal of Biomechanics · 2025-03-26 · 1 citations

Healthy human induced pluripotent stem cell-derived cardiomyocytes exhibit sex dimorphism even without the addition of hormones

Stem Cells · 2025-06-19 · 2 citations

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a valuable cell type for studying human cardiac health and disease in vitro. However, it is not known whether hiPSC-CMs display sex dimorphism and therefore whether sex should be incorporated as a biological variable in in vitro studies that include this cell type. To date, the vast majority of studies that utilize hiPSC-CMs do not include both male and female sex nor stratify results based on sex because it is challenging to amass such a cohort of cells. Here, we generated 3 female and 3 male hiPSC lines from adult left ventricular cardiac fibroblasts as a resource for studying sex differences in in vitro cardiac models. We used this resource to generate hiPSC-CMs and maintained them in basal media without exogenous hormones. Functional assessment of CMs showed enhanced calcium handling in female-derived hiPSC-CMs relative to male. Bulk RNA sequencing revealed over 300 differentially expressed genes (DEGs) between male and female hiPSC-CMs. Gene ontology analysis of DEGs showed distinct differences in pathways related to cardiac pathology including cell-cell adhesion, metabolic processes, and response to ischemic stress. Differential expression of the sodium channel auxiliary unit SCN3B was found and validated through patch-clamp measurements of sodium currents, showing increased peak amplitude and window current in female hiPSC-CMs. These findings highlight the importance of considering sex as a variable when conducting studies to evaluate aspects of human cardiac health and disease related to CM function.

Development of an iPSC-based screening platform identifying enhancers of chondrogenesis

Osteoarthritis and Cartilage Open · 2025-09-17 · 1 citations

Objective: There is currently no long-term treatment for the repair of damaged cartilage and osteoarthritis (OA). Induced pluripotent stem cells (iPSCs) are an ideal cell source for screening platforms due to their ability to self-renew and differentiate to cell types that would otherwise require invasive surgeries to obtain, such as chondrocytes and mesenchymal stromal cells (MSCs). Here, we developed an iPSC-based screening platform and tested previously described pro-chondrogenic small molecule compounds, to determine their potential to identify hits. Design: . Glycosaminoglycan (GAG) synthesis was quantified by a 1,9- dimethylmethylene blue (DMMB) assay. Results: After 14 days of chondrogenesis, forskolin, baicalin and sesamin enhanced GAG synthesis in the iCPs, and forskolin enhanced GAG synthesis in the iNCC-MSCs, while no small molecule compounds enhanced GAG synthesis in the BM-MSCs. Conclusion: Our findings further demonstrate how the small molecules pro-chondrogenic effects are dependent on the screening platform conditions, including the cell type, molecule concentration, 3D culture, hypoxia, and the inclusion of additional growth factors. The iPSC-based screening platform developed has the potential to identify disease modifying OA drugs (DMOADs) in novel compound screening libraries.

DMSO-free cryopreservation of hiPSC-derived cardiomyocytes: Low temperature characterization and protocol development

Research Square · 2025-04-14

Defective chaperone-mediated autophagy in the retinal pigment epithelium of age-related macular degeneration patients

EMBO Molecular Medicine · 2025-10-30 · 6 citations

Autophagy is one of the main intracellular recycling systems and its impairment is considered a primary hallmark of the aging process. Defective macroautophagy in the retinal pigment epithelium (RPE) has been described in age-related macular degeneration (AMD), a blindness-causing disease that affects roughly 200 million patients worldwide. The relevance of chaperone-mediated autophagy (CMA), a selective type of autophagy for proteins containing a KFERQ-like motif, in RPE cell biology and homeostasis remains to be elucidated. Here we describe decreased CMA activity in the RPE of AMD patients compared to healthy age-matched controls, along with accumulation of substrate proteins, and in donor-derived iPSC-RPE cells, which we used to further characterize AMD-associated alterations of cellular homeostasis derived from proteotoxicity. Treatment with CA77.1 (CMA activator) restores proteostasis and remodels specific subsets of the proteome in cells from healthy and AMD donors. CA77.1-treated AMD iPSC-RPE display reduced oxidative stress and improved mitochondrial function. These findings may explain the specific vulnerability of the RPE during AMD and shed light on CMA as a new druggable target for this as-of-now incurable disease.

DMSO-free cryopreservation of hiPSC-derived cardiomyocytes: low temperature characterization and protocol development

Stem Cell Research & Therapy · 2025-06-10 · 2 citations

BACKGROUND: Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have attracted significant interest for use in disease modeling, drug discovery and potential therapeutic applications. However, conventional hiPSC-CM cryopreservation protocols largely use dimethyl sulfoxide (DMSO) as the cryoprotectant (CPA), which is linked with a loss of post-thaw recovery and function for various cell types and is not ideal for therapeutic protocols. Additionally, the effect of freezing parameters such as cooling rate and nucleation temperature on post-thaw recovery of hiPSC-CMs has not been explored. METHODS: hiPSC-CMs were generated by Wnt pathway inhibition, followed by sodium l-lactate purification. Subsequently, biophysical characterization of the cells was performed. A differential evolution (DE) algorithm was utilized to determine the optimal composition of a mixture of a sugar, sugar alcohol and amino acid to replace DMSO as the CPA. The hiPSC-CMs were subjected to controlled-rate freezing at different cooling rates and nucleation temperatures. The optimum freezing parameters were identified by post-thaw recoveries and the partitioning ratio obtained from low temperature Raman spectroscopy studies. The post-thaw osmotic behavior of hiPSC-CMs was studied by measuring diameter of cells resuspended in the isotonic culture medium over time. Immunocytochemistry and calcium transient studies were performed to evaluate post-thaw function. RESULTS: hiPSC-CMs were found to be slightly larger than hiPSCs and exhibited a large osmotically inactive volume. The best-performing DMSO-free solutions enabled post-thaw recoveries over 90%, which was significantly greater than DMSO (69.4 ± 6.4%). A rapid cooling rate of 5 °C/min and a low nucleation temperature of -8 °C was found to be optimal for hiPSC-CMs. hiPSC-CMs displayed anomalous osmotic behavior post-thaw, dropping sharply in volume after resuspension. Post-thaw function was preserved when hiPSC-CMs were frozen with the best-performing DMSO-free CPA or DMSO and the cells displayed similar cardiac markers pre-freeze and post-thaw. CONCLUSIONS: It was shown that a CPA cocktail of naturally-occurring osmolytes could effectively replace DMSO for preserving hiPSC-CMs while preserving morphology and function. Understanding the anomalous osmotic behavior and managing the excessive dehydration of hiPSC-CMs could be crucial to improve post-thaw outcomes. Effective DMSO-free cryopreservation would accelerate the development of drug discovery and therapeutic applications of hiPSC-CMs.

The AKT2/SIRT5/TFEB pathway as a potential therapeutic target in non-neovascular AMD

Nature Communications · 2024-07-21 · 28 citations

Non-neovascular or dry age-related macular degeneration (AMD) is a multi-factorial disease with degeneration of the aging retinal-pigmented epithelium (RPE). Lysosomes play a crucial role in RPE health via phagocytosis and autophagy, which are regulated by transcription factor EB/E3 (TFEB/E3). Here, we find that increased AKT2 inhibits PGC-1α to downregulate SIRT5, which we identify as an AKT2 binding partner. Crosstalk between SIRT5 and AKT2 facilitates TFEB-dependent lysosomal function in the RPE. AKT2/SIRT5/TFEB pathway inhibition in the RPE induced lysosome/autophagy signaling abnormalities, disrupted mitochondrial function and induced release of debris contributing to drusen. Accordingly, AKT2 overexpression in the RPE caused a dry AMD-like phenotype in aging Akt2 KI mice, as evident from decline in retinal function. Importantly, we show that induced pluripotent stem cell-derived RPE encoding the major risk variant associated with AMD (complement factor H; CFH Y402H) express increased AKT2, impairing TFEB/TFE3-dependent lysosomal function. Collectively, these findings suggest that targeting the AKT2/SIRT5/TFEB pathway may be an effective therapy to delay the progression of dry AMD.

The Complement Factor H (Y402H) risk polymorphism for age-related macular degeneration affects metabolism and response to oxidative stress in the retinal pigment epithelium

Free Radical Biology and Medicine · 2024-11-01 · 6 citations

Healthy human induced pluripotent stem cell-derived cardiomyocytes exhibit sex dimorphism even without the addition of hormones

bioRxiv (Cold Spring Harbor Laboratory) · 2024-05-31

Abstract Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are a valuable cell type for studying human cardiac health and disease in vitro . However, it is not known whether hiPSC-CM display sex dimorphism and therefore whether sex should be incorporated as a biological variable in in vitro studies that include this cell type. To date, the vast majority of studies that utilize hiPSC-CM do not include both male and female sex nor stratify results based on sex because it is challenging to amass such a cohort of cells. Here we generated three female and three male hiPSC-lines from adult left ventricular cardiac fibroblasts as a resource for studying sex differences in in vitro cardiac models. We used this resource to generate hiPSC-CM and maintained them in basal media without exogenous hormones. Functional assessment of CM showed enhanced calcium handling in female-derived hiPSC-CM relative to male. Bulk RNA sequencing revealed over 300 differentially expressed genes (DEG) between male and female hiPSC-CM. Some of the DEG are X and Y-linked genes and many are implicated in cardiac health and disease including potassium channels which could account for net differences in calcium handling shown here. Gene ontology analysis of DEG showed distinct differences in pathways related to cardiac pathology including cell-cell adhesion, metabolic processes, and response to ischemic stress. These findings highlight the importance of considering sex as a variable when conducting studies to evaluate aspects of human cardiac health and disease related to cardiomyocyte function.