Current Perspectives on Nucleus Pulposus Fibrosis in Disc Degeneration and Repair

Round 1

Reviewer 1 Report

This was an interesting review and I found it enlightening about the role of Collagen II. In dogs according to Gupta et al. oral supplementation with Undenatured collagen II decreases inflammation in joints. I wonder about the effects on the NP..just a thought

Well done

Author Response

Local recovery collagen II is critical to disc repair and its mechanics. Several preclinical investigations demonstrated that supplementation of undenatured collagen II (Peal et al, 2007; Gupta et al, 2009; Gupta et al, 2011) alone or in combination with glucosamine or chromemate could reduce arthritic pain without significant toxicity in dog or horse. Unlike synovial joints, NP in the disc is gelatinous due to the large amount of proteoglycans. Oral intake of glucosamine or chondroitin sulfate instead of collagen II has been explored with mixed results (Kadow et al, 2015; Blitterswijk et al, 2003). To date, there has been no report on how oral collagen II (UC-II) supplementation impact on disc degeneration or fibrosis.   

Reviewer 2 Report

This is a well written and comprehensive manuscript, describing and stressing all important details in teh DDD. Of course, other facors are also in play, that are not described by the authors. However, these are not important here, as the text focuses specifically on the NP. I recommend the paper for publication in its curret form. It is interesting and summarises the data related to NP fibrosis and DDD precisely. 

Author Response

We are grateful for the comments. We hope this review provides a unique perspective onto disc degeneration mechanism and facilitates future research of its pathogenesis and therapeutic apporaches.