Reply to Yurekli et al.

We would like to express our thanks for your correspondence [1] about our article: Omentum support for cardiac regeneration in ischaemic cardiomyopathy models: a systematic scoping review [2] and for this opportunity to reply.

In our article, we addressed the following question: what potential effects may the omentum have as a supporting tissue for bioengineered myocardial regeneration? The scoping review included a heterogenous set of 11 studies, consistent with current techniques in myocardial regeneration and bioengineering research [3]. Six additional studies were separated out into Tables 5 and 6 (as they were too different to be comparable).

It was our utmost interest to ensure we were able to analyse these studies using the most unbiased criteria. Despite the heterogeneity of the approaches used, we were still able to compare the effects of a pedicled omental flap as support for bioengineering aimed at myocardial regeneration—according to reported findings of each study (regardless of the exact bioengineering technique used). It is because of the heterogenous nature of the studies, not despite it, that a systematic scoping review was chosen as the method to assess whether the wide variety of techniques anticipated by our search criteria might benefit from omental reinforcement. We are therefore confident that we addressed the central question regarding these studies, which could also be re-stated as: ‘is the use of a pedicled omental flap a promising adjunct for bioengineering approaches to myocardial regeneration (based on the existing literature)?’.

Regarding your comment about the study by Kainuma et al. [4] and the engrafted area (Table 2) [2]; we compared the effects at day 7 and day 28 (similar intervals to those presented in many other studies). We do acknowledge that at day 3, there was not a statistically significant effect—engrafted area remaining of 0.35 mm² with omentum support and 0.25 mm² without [4]. Graphical representation of this (Figure 3h of the original article) [4] makes it clear that the omentum-supported myoblast cell sheets had a more gradual loss of donor cells (reducing engraftment area) up to day 28. In contrast, without omentum support, there was a steep drop off of donor cells (engrafted area) before day 7. The starting number (on ‘day zero’) of labelled donor cells was similar in all their bioengineered cell sheet groups. These effects were statistically significant only by day 7 and persisted until day 28, with the absolute numbers clearly favouring omentum support.

Regarding the study by Lilyanna et al. [5], this was the only study we found reporting that omentum support did not result in an increase in cell retention. We emphasized this in our paragraph titled ‘Transplanted Cell Retention’ where we concluded that most studies presented improved engraftment outcomes with supportive omentopexy, except for this one.

We would like to acknowledge the importance of your comments, especially your mention of modification with ‘some medications’, which in the tissue engineering space may be extended to signalling factors, cells and biomaterials. In summary, we agree that omentopexy alone may be insufficient based on the current literature, but as a support for bioengineered tissue, it may help for the translation of findings from the bench to the bedside.

REFERENCES