Gap junctions in human synovial cells and tissue.

Little is known about how synovial cells coordinate function through direct communication. Prior research has shown that gap junctions are common in epithelial and cardiac tissues, but their presence in synovial cells remains unclear. This gap motivated investigations into whether synovial cells form functional junctions. No prior work had resolved whether these junctions exist in cultured synovial cells or in synovial tissue. It was already known that gap junctions enable ion and molecule transfer between cells. However, the role of such junctions in synovial biology is not established. That uncertainty drove the need to confirm the presence and function of gap junctions in synovial cells. This study aimed to address these unanswered questions.

The aim was to determine whether synovial cells form functional gap junctions. The specific problem addressed was the lack of evidence for intercellular communication in synovial cells. The motivation came from the need to understand how synovial cells might coordinate function. This study sought to confirm the presence of gap junctions in cultured synovial cells and in synovial tissue. The researchers proposed to use multiple methods to assess junctional communication. They intended to measure electrical coupling and visualize junctional proteins. The goal was to establish whether synovial cells form junctions and to identify the proteins involved. This work could clarify the physiological relevance of synovial cell communication.

The researchers used the nystatin perforated-patch method to measure electrical coupling between cells. Fluorescent dye transfer was employed to confirm intercellular communication. Immunostaining was used to detect connexin43 in cultured and tissue samples. Transmission electron microscopy provided structural evidence of gap junctions. Immunoblotting confirmed the presence of connexin43 protein. Voltage step responses were recorded to assess junctional current flow. Cell aggregates were analyzed for resistance values. Synovial tissue explants were examined for junctional networks.

Functional gap junctions were observed in cultured synovial cells. The average resistance between cells was 300 ± 150 MOmega in small aggregates. Dye transfer confirmed intercellular communication in cultured cells. Connexin43 was detected in cultured cells and synovial membranes. Punctate fluorescent regions indicated junctional localization of connexin43. Transmission electron microscopy showed 2-nm intermembrane gaps typical of junctions. Synovial tissue explants contained junctional networks of over 40 cells. These findings suggest that synovial cells form functional junctions.

The authors propose that synovial cells form functional gap junctions. These junctions enable ionic and molecular communication between cells. The presence of connexin43 was verified in cultured and tissue samples. The junctions were observed in both cultured and native synovial cells. The size of junctional networks exceeded 40 cells in tissue explants. The study suggests that gap junctions are a regular feature of synovial cells. The physiological role of these junctions remains unknown. The researchers suggest that intercellular communication may serve an unrecognized function.