# Temporal expression dynamics of glypicans during hiPSC cardiac differentiation

## TL;DR

This study tracks how glypicans, which are cell surface proteins, change over time during the process of turning stem cells into heart cells.

## Contribution

The study provides a detailed temporal map of glypican expression during cardiac differentiation of human pluripotent stem cells.

## Key findings

- GPC3 and GPC6 are upregulated during the WNT activation phase of differentiation.
- GPC4 is suppressed after WNT inhibition and remains low during cardiac commitment.
- GPC2 and GPC5 peak during cardiac progenitor formation, while GPC1 increases after cardiac specification.

## Abstract

Human pluripotent stem cells (hPSCs) offer a versatile platform for modeling human cardiac development and generating cardiomyocytes for research and translational applications. Cardiac differentiation protocols are well established and rely on the sequential activation and inhibition of WNT, BMP, and FGF signaling pathways to guide lineage progression. While these intracellular signaling events are well characterized, less attention has been given to the temporal behavior of extracellular components present at the cell surface during differentiation. Glypicans (GPCs) are a family of membrane-bound heparan sulfate proteoglycans within the glycocalyx that are known to interact with morphogens in multiple developmental contexts. In this study, we profiled the expression of GPC1-6 during a standard chemically defined cardiac differentiation protocol, in the absence of targeted interventions. Gene expression analysis across stages revealed distinct, stage-associated patterns: GPC3 and GPC6 were upregulated during the WNT activation phase; GPC4 was suppressed after WNT inhibition and maintained low during cardiac commitment. GPC2 and GPC5 expressions peaked during the formation of cardiac progenitors, and GPC1 expression increased following cardiac specification. These findings provide a temporal map of GPC expression coinciding with established differentiation stages, demonstrating that members of the glypican family are dynamically expressed during human cardiac differentiation. By documenting when specific glypicans are expressed during a commonly used differentiation workflow, this study offers a descriptive reference framework that may inform future mechanistic studies investigating how extracellular components intersect with canonical cardiac signaling pathways.