Celector^®: An Innovative Technology for Quality Control of Living Cells

Round 1

Reviewer 1 Report

The manuscript titled Celector®: an innovative technology for quality control of 2 living cells as a drug-screening platform describes the use of Celector® for cell analysis. Overall presentation of the results is fine. However, some revisions are suggested:

1. The titles drug-screening platform, but it is not clear what drug-screening is demonstrated in the manuscript? The title might be misleading. 

2. It is not clear whether Celector® is developed as a part of this manuscript or just its application is demonstrated. Please clarify it in introduction and methodology section.

3. The novelty of the work is not clear. Authors should compare their results with related techniques.

4. Typos should be corrected e.g., 1mL min = 1mL min^-1. Check throughout the manuscript.

Author Response

Detailed answers to Reviewer 1 in the attached file. Thank for the comments

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors. The problem of qualitative analysis of cell cultures is still a major issue in laboratories involved in ATMP production, and to a lesser extent in the screening of new drugs.

It is most appropriate to develop new control methods in the production process. Current control methods are based on only a few long-used tests.

Unfortunately, despite the knowledge of the various control methods, I find it difficult to imagine using a new method. I would therefore ask you to complete in your work:

1. A diagram of how the test method works - how the device works.

2. The test procedure - the test algorithm.

3. The possibility of validation. Possible acceptance criteria for the cell lines tested.

Reference how the results are presented for primary cultures to be used for ATMP production. 

The article also lacks coherence. The thesis statements in the introduction only loosely correspond with the rest of the article. After reading the article, I do not see how this system could be used in my laboratory burdened with designing ATMP products and conducting new drug screening. I think the aim of the article was to attract potential future customers to the system. So far this has not been successful.

Author Response

Detailed answers to Reviewer 2 in the attached file. Thank for the comments

Author Response File: Author Response.docx

Reviewer 3 Report

The authors in this work look for a method to control the stability and/or quality of cells used in diverse cell based assays, to do that they make use of a device called Celector®.  This device takes advantages of Non-Equilibrium Earth Gravity Assisted Dynamic fractionation (NEEGA-DF) that combines laminar liquid flow with gravity to separate cells based on their physical characteristics, as cells having different physical characteristics acquire different velocity inside the capillary channel and elute at different time, with no labelling required and therefore preserving the native cell properties. The authors use a Celector® equipped with a micro-camera for cell detection, a specifically designed software for image acquisition and post-processing, and data analysis. The output of the instrument is a multi-parametric fractogram representing number, size and shape of the eluted cells as a function of fractionation time; they claim that this fractogram represents a fingerprint of the cell sample.

Thus, this instrument serves as a quality control device and to fraction the population by their physical characteristics.

They use two types of cell lines, the promyeloblasts HL60 and the colorectal cancer cells SW620. They use the Celector® to separate the cell culture in each passage, purifying the cells (elution minutes from 5 to 15) from debris that elutes before. They also study the number of cells that elute before (F1) or after the maximum (F2).

With this protocol, the authors demonstrate that the cells in culture increase their size in each passage. They also show that the cells that are purified in each passage maintain the doubling time that is not stable in the non-purified passages. In addition, they show that the device can purify the viable cells after being thawed and demonstrate how harmful is the freezing solution if it is not eliminated before plating the cells.

In my opinion, they could have performed better tests to demonstrate that the cells they purify and identify as healthy and stable are in fact healthy and stable cells. For example, apoptosis assays, immunostainings to show that cell appearance remains constant or cell cycle studies to demonstrate that the cell cycle phases are not altered. So, although the idea is interesting, in my opinion the work is very preliminary and if the authors want to implement the Celector® as a quality control standard a more complete study should be provided.

Author Response

Detailed answers to Reviewer 3 in the attached file. Thank for the comments

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The revised version can be accepted for publication. Since this is not a protocol (paper), authors should present section 2.4 (Celector® test procedure) in the form of a paragraph (remove bullets, merge and restructure some sentences to fit-well in the paragraph). It can be done at proofreading stage as well.

Reviewer 2 Report

Dear authors.

I kindly thank you for your comprehensive replies and the corrections made to the publication. I wish you success in the further development of the technology and the analyser.