title: Extracellular matrix of mechanically stretched cardiac fibroblasts improves viability and metabolic activity of ventricular cells.
abstract: BACKGROUND
  In heart, the extracellular matrix (ECM), produced by cardiac fibroblasts, is a potent regulator of heart's function and growth, and provides a supportive scaffold for heart cells in vitro and in vivo. Cardiac fibroblasts are subjected to mechanical loading all the time in vivo. Therefore, the influences of mechanical loading on formation and bioactivity of cardiac fibroblasts ECM should be investigated.
  
  
  METHODS
  Rat cardiac fibroblasts were cultured on silicone elastic membranes and stimulated with mechanical cyclic stretch. After removing the cells, the ECMs coated on the membranes were prepared, some ECMs were treated with heparinase II (GAG-lyase), then the collagen, glycosaminoglycan (GAG) and ECM proteins were assayed. Isolated neonatal rat ventricular cells were seeded on ECM-coated membranes, the viability and lactate dehydrogenase (LDH) activity of the cells after 1-7 days of culture was assayed. In addition, the ATPase activity and related protein level, glucose consumption ratio and lactic acid production ratio of the ventricular cells were analyzed by spectrophotometric methods and Western blot.
  
  
  RESULTS
  The cyclic stretch increased collagen and GAG levels of the ECMs, and elevated protein levels of collagen I and fibronectin. Compared with the ECMs produced by unstretched cardiac fibroblasts, the ECMs of mechanically stretched fibroblasts improved viability and LDH activity, elevated the Na⁺/K⁺-ATPase activity, sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA) activity and SERCA 2a protein level, glucose consumption ratio and lactic acid production ratio of ventricular cells seeded on them. The treatment with heparinase II reduced GAG levels of these ECMs, and lowered these metabolism-related indices of ventricular cells cultured on the ECMs.
  
  
  CONCLUSIONS
  Mechanical stretch promotes ECM formation of cardiac fibroblasts in vitro, the ECM of mechanically stretched cardiac fibroblasts improves metabolic activity of ventricular cells cultured in vitro, and the GAG of the ECMs is involved in regulating metabolic activity of ventricular cells.
authors: 1. Lab of Biomaterial, Tianjin Institute of Medical Equipment, Academy of Military Medical Science, Tianjin, China;
authors: Yong
authors: Y
authors: Guo
authors: Qiang-cheng
authors: QC
authors: Zeng
authors: Chun-qiu
authors: CQ
authors: Zhang
authors: Xi-zheng
authors: XZ
authors: Zhang
authors: Rui-xin
authors: RX
authors: Li
authors: Ji-min
authors: JM
authors: Wu
authors: Jing
authors: J
authors: Guan
authors: Lu
authors: L
authors: Liu
authors: Xin-chang
authors: XC
authors: Zhang
authors: Jian-yu
authors: JY
authors: Li
authors: Zong-ming
authors: ZM
authors: Wan
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D005109:Extracellular Matrix; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006352:Heart Ventricles / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D019763:Heparin Lyase / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019344:Lactic Acid / Q000096:biosynthesis; D032383:Myocytes, Cardiac / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D013314:Stress, Mechanical
chemical_list: D019344:Lactic Acid; D007770:L-Lactate Dehydrogenase; D000251:Adenosine Triphosphatases; D019763:Heparin Lyase; D005947:Glucose
keywords: cardiac fibroblast; extracellular matrix; glycosaminoglycan; mechanical stretch; metabolism.