Reviewer's report 
 TGF beta-1 and PDGF AA override collagen type I inhibition of proliferation in human liver Title: 
connective tissue cells 
 1  31 August 2004 Version: Date: 
 Minoti Apte Reviewer: 
Reviewer's report: 
General 
This study examines the concept that fibroblasts/stellate cells in diseased liver do not respond to normal physiological controls for proliferation, given that stellate cell proliferation is evident in fibrosing liver disease despite the increase in collagen deposition (in normal conditions collagen 
acts as an inhibitor of cell proliferation. 
The authors have compared the responses of primary cultures of liver connective tissue cells 
(LCTC) and skin fibroblasts (SF) from patients with liver fibrosis undergoing spleno-renal or 
porto-caval anastomosis, to growth factors in the presence of collagen I and IV. They report that 
LCTC are more sensitive to the proliferative effects of PDGF AA; this growth factor was able to overcome the collagen-induced inhibition of proliferation in LCTC but not in SF. Similar effects were observed for TGFb in LCTC. SF proliferation was decreased by TGFb itself. The inhibition of SF 
proliferation by collagen was not reversed by TGFb. 
------------------------------------------------------------------------------- Major Compulsory Revisions (that the author must respond to before a decision on publication can be reached) 
1. Very little detail has been provided regarding the isolation and culture of LCTC. What was the 
purity of these cultures? It would be assumed that the cultures were a mixture of periportal and pericentrovenular fibroblasts, hepatic stellate cells and smooth muscle cells. Were these cells 
characterised in any way? 
2. The choice of skin fibroblasts for comparison was interesting. It may be suggested that stellate cells/fibroblasts from normal liver would be more appropriate tissue specific controls. 3. The selection of the PDGF isoform AA was also intriguing. Most of the evidence in the literature 
indicates that PDGF BB is the more potent mitogenic isoform. Can the authors discuss their choice 
of the PDGF isoform? 4. The exact number (n) of separate cell cultures used for each parameter should be specified. Statistical significance (p values should also be provided). 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the author can be trusted to correct) 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) It would be of interest to know whether the effects of PDGF are mediated by an upregulation of the 
receptors for this growth factor on the cell surface. Is data available regarding PDGF receptor 
expression on cells cultured under the various conditions used in the experimental set up - plastic, collagen coated wells, presence and absence of PDGF and presence and absence of TGFb (given that the effect of TGFb may be mediated via increased PDGF production by LCTC and an autocrine 
loop)? 
 Unable to decide on acceptance or rejection until the authors have responded to the What next?: 
major compulsory revisions 
 An article whose findings are important to those with closely related research Level of interest: 
interests 
 Acceptable Quality of written English: 
 No Statistical review: 
Declaration of competing interests: 
None 
Reviewer's report 
 TGF beta-1 and PDGF AA override collagen type I inhibition of proliferation in human liver Title: 
connective tissue cells 
 1  31 August 2004 Version: Date: 
 Minoti Apte Reviewer: 
Reviewer's report: 
General 
This study examines the concept that fibroblasts/stellate cells in diseased liver do not respond to normal physiological controls for proliferation, given that stellate cell proliferation is evident in fibrosing liver disease despite the increase in collagen deposition (in normal conditions collagen 
acts as an inhibitor of cell proliferation. 
The authors have compared the responses of primary cultures of liver connective tissue cells 
(LCTC) and skin fibroblasts (SF) from patients with liver fibrosis undergoing spleno-renal or 
porto-caval anastomosis, to growth factors in the presence of collagen I and IV. They report that 
LCTC are more sensitive to the proliferative effects of PDGF AA; this growth factor was able to overcome the collagen-induced inhibition of proliferation in LCTC but not in SF. Similar effects were observed for TGFb in LCTC. SF proliferation was decreased by TGFb itself. The inhibition of SF 
proliferation by collagen was not reversed by TGFb. 
------------------------------------------------------------------------------- Major Compulsory Revisions (that the author must respond to before a decision on publication can be reached) 
1. Very little detail has been provided regarding the isolation and culture of LCTC. What was the 
purity of these cultures? It would be assumed that the cultures were a mixture of periportal and pericentrovenular fibroblasts, hepatic stellate cells and smooth muscle cells. Were these cells 
characterised in any way? 
2. The choice of skin fibroblasts for comparison was interesting. It may be suggested that stellate cells/fibroblasts from normal liver would be more appropriate tissue specific controls. 3. The selection of the PDGF isoform AA was also intriguing. Most of the evidence in the literature 
indicates that PDGF BB is the more potent mitogenic isoform. Can the authors discuss their choice 
of the PDGF isoform? 4. The exact number (n) of separate cell cultures used for each parameter should be specified. Statistical significance (p values should also be provided). 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the author can be trusted to correct) 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) It would be of interest to know whether the effects of PDGF are mediated by an upregulation of the 
receptors for this growth factor on the cell surface. Is data available regarding PDGF receptor 
expression on cells cultured under the various conditions used in the experimental set up - plastic, collagen coated wells, presence and absence of PDGF and presence and absence of TGFb (given that the effect of TGFb may be mediated via increased PDGF production by LCTC and an autocrine 
loop)? 
 Unable to decide on acceptance or rejection until the authors have responded to the What next?: 
major compulsory revisions 
 An article whose findings are important to those with closely related research Level of interest: 
interests 
 Acceptable Quality of written English: 
 No Statistical review: 
Declaration of competing interests: 
None 
Please review this paper.
user
Reviewer's report 
 TGF beta-1 and PDGF AA override collagen type I inhibition of proliferation in human liver Title: 
connective tissue cells 
 1  31 August 2004 Version: Date: 
 Minoti Apte Reviewer: 
Reviewer's report: 
General 
This study examines the concept that fibroblasts/stellate cells in diseased liver do not respond to normal physiological controls for proliferation, given that stellate cell proliferation is evident in fibrosing liver disease despite the increase in collagen deposition (in normal conditions collagen 
acts as an inhibitor of cell proliferation. 
The authors have compared the responses of primary cultures of liver connective tissue cells 
(LCTC) and skin fibroblasts (SF) from patients with liver fibrosis undergoing spleno-renal or 
porto-caval anastomosis, to growth factors in the presence of collagen I and IV. They report that 
LCTC are more sensitive to the proliferative effects of PDGF AA; this growth factor was able to overcome the collagen-induced inhibition of proliferation in LCTC but not in SF. Similar effects were observed for TGFb in LCTC. SF proliferation was decreased by TGFb itself. The inhibition of SF 
proliferation by collagen was not reversed by TGFb. 
------------------------------------------------------------------------------- Major Compulsory Revisions (that the author must respond to before a decision on publication can be reached) 
1. Very little detail has been provided regarding the isolation and culture of LCTC. What was the 
purity of these cultures? It would be assumed that the cultures were a mixture of periportal and pericentrovenular fibroblasts, hepatic stellate cells and smooth muscle cells. Were these cells 
characterised in any way? 
2. The choice of skin fibroblasts for comparison was interesting. It may be suggested that stellate cells/fibroblasts from normal liver would be more appropriate tissue specific controls. 3. The selection of the PDGF isoform AA was also intriguing. Most of the evidence in the literature 
indicates that PDGF BB is the more potent mitogenic isoform. Can the authors discuss their choice 
of the PDGF isoform? 4. The exact number (n) of separate cell cultures used for each parameter should be specified. Statistical significance (p values should also be provided). 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the author can be trusted to correct) 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) It would be of interest to know whether the effects of PDGF are mediated by an upregulation of the 
receptors for this growth factor on the cell surface. Is data available regarding PDGF receptor 
expression on cells cultured under the various conditions used in the experimental set up - plastic, collagen coated wells, presence and absence of PDGF and presence and absence of TGFb (given that the effect of TGFb may be mediated via increased PDGF production by LCTC and an autocrine 
loop)? 
 Unable to decide on acceptance or rejection until the authors have responded to the What next?: 
major compulsory revisions 
 An article whose findings are important to those with closely related research Level of interest: 
interests 
 Acceptable Quality of written English: 
 No Statistical review: 
Declaration of competing interests: 
None 
assistant