Growth and stretch response of human exstrophy bladder smooth muscle cells: molecular evidence of normal intrinsic function.
OBJECTIVE
To establish primary cultures of smooth muscle cells (SMC) from human exstrophic bladders (E-SMC), and determine their in vitro growth dynamics and responses to mechanical stretch.


METHODS
Primary cultures of E-SMC from three patients were established from exstrophic bladder tissue using an explant method. Growth dynamics were assessed using tetrazolium-dye uptake. The DNA synthesis rate in response to cyclic stretch-relaxation was determined with thymidine-incorporation assays. Expression of the SMC mitogen heparin-binding epidermal growth factor-like growth factor (HB-EGF) mRNA in response to mechanical stretch was determined using semiquantitative reverse transcription-polymerase chain reaction.


RESULTS
The approximate doubling time of the E-SMC grown in the presence of serum was 4 days, consistent with growth rates of SMC reported previously. E-SMC exposed to stretch had greater DNA synthesis, albeit to a lesser extent than previously seen with non-exstrophic SMC. The expression of HB-EGF was also increased in cells exposed to mechanical stimuli, consistent with our previous finding of stretch-regulated HB-EGF gene expression in bladder SMC.


CONCLUSIONS
E-SMC had growth characteristics similar to those previously reported in non-exstrophic cells. E-SMC also had stretch-induced expression of HB-EGF mRNA. These observations provide evidence that despite development in an abnormal defunctionalized state, E-SMC retain the potential for normal growth, and may modulate this response through mechanisms similar to those operating in normal bladder SMC.
Orsola
Anna
A
Urological Diseases Research Center, Department of Urology, Children's Hospital Boston and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
Estrada
Carlos R
CR
Nguyen
Hiep T
HT
Retik
Alan B
AB
Freeman
Michael R
MR
Peters
Craig A
CA
Adam
Rosalyn M
RM
D001746:Bladder Exstrophy / Q000473:pathology* / Q000503:physiopathology; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism; D005260:Female; D066257:Heparin-binding EGF-like Growth Factor; D006801:Humans; D007231:Infant, Newborn; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013314:Stress, Mechanical
C587883:HBEGF protein, human; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D004247:DNA