Review for 10.1186/s12876-024-03253-4 (2024)

Title: A new model of portal vein thrombosis in rats with cirrhosis induced by partial portal
vein ligation plus carbon tetrachloride and intervened with rivaroxaban
Version: 2 Date: 02 Mar 2024
Reviewer:  Johannes Chang
Reviewer's report:
Guo et al. established an animal model of portal vein thrombosis and cirrhosis. They employed
the partial portal vein ligation model in combination with the CCL4-model and demonstrated
that rats developed cirrhosis along with signs of intra- and extrahepatic thrombosis, as evidenced
by visible or surrogate parameters of thrombosis and endothelial dysfunction. Additionally,
they observed that the administration of rivaroxaban in this setting appeared to ameliorate this
process, although the underlying pathomechanism remains unclear.
The strength of the study lies in its robust data and the high standard and technical soundness
of the methods employed. The analysis was appropriately executed and not overly complex.
However, there are several points that need to be addressed:
Major:
Methodology:
- A significant concern is the absence of a CCL4-only control group. It is essential to establish
that the observed findings are not solely due to cirrhosis. While it is known, to the best of my
knowledge, that CCL4-induced cirrhosis is not associated with extrahepatic thrombosis, the
same needs to be confirmed for all other markers described in the paper. If this knowledge exists,
it should be referenced, or the rationale for not utilizing this crucial control group should be
discussed.
- Regarding the PPVL-only control group: clarification is needed regarding the timing of
sacrifice in the PPVL-only group. Was it performed after 3 weeks or 10 weeks? This information
is relevant as portal pressure peaks 2-4 weeks after the initial procedure and decreases thereafter.
This aspect also warrants discussion in the relevant section.
- As this is a methodology paper, more details about animal outcomes, complications, etc., are
necessary. Did all animals survive, and if not, what were the reasons for their respective deaths?
Why were different numbers of animals used for the individual groups? For the Rivaroxaban
group, were there any bleeding complications? This information is crucial for the main message
of the paper.
Clinical relevance:
- While the issue addressed in the study is relevant, the clinical translation needs to be articulated
more clearly. Would the implication be that patients with cirrhosis at risk of bleeding should
undergo anticoagulation therapy? Anticoagulation therapy is approached cautiously in this
patient population due to bleeding risks. What would be the clinical implications of this model?
Although rivaroxaban shows promise in reducing thrombosis in this context, this finding is not
groundbreaking. Moreover, advancements in TIPS procedures in this context have significantly
evolved (Recanalzation via TIPS). Additionally, more literature on anticoagulation therapy and
cirrhosis should be discussed, as there are relevant studies worth mentioning.
- Mechanism: While some experiments were conducted to confirm the pro- and anticoagulatory
environment, more in-depth exploration of pathway mechanisms is lacking. Do the authors
possess plasma samples and have the capability to conduct proteomics analysis on the groups
showing the most significant differences? This approach could enhance the message of the
paper. Given the extensive discussion on endothelial dysfunction in cirrhosis, the reasons for
thrombosis in this model (no thrombosis without CCL4!) should be discussed in greater detail,
considering the methodological focus of the paper.
Minor:
- CCL4-induced cirrhosis is a widely accepted model; however, it is recognized that it lacks
clinical correlation and is understood as primarily a toxic model accelerated by Phenobarbital
usage. This limitation should be discussed since the etiology of cirrhosis is always an important
issue.
- In the Methods section, it is stated that a 20 G needle was inserted into the portal vein. Perhaps
the authors meant "next to" or "adjacent to." The description elsewhere in the text is correct.
- While the use of ultrasound is commendable, it should be noted that the standard for measuring
portal pressure is measuring in-vivo portal pressure. This limitation should be acknowledged.
Additionally, more details are needed on how Doppler sonography was performed. Isn`t the
Philips IU22 typically used for humans? The methodology for measuring flow velocity in such
a small diameter should be described more thoroughly.
- It would also be intriguing to explore a model of extra- and intrahepatic thrombosis without
cirrhosis, this could be discussed for future projects