A GLP Chronic Study to Evaluate the Biological Effects and Systemic Toxicity of Rejuve (IDSD) Implantation in an Ovine Intervertebral Disc Model

DOI: https://doi.org/10.57212/EMYN8297

Authors: Lopes-Berkas, V.; Urtz, M.; Creamer-Henter, M. – Synchrony Labs

Publisher: Spinal Simplicity LLC

IACUC Study Number: 190-03-18


The purpose of this IACUC approved study was to evaluate and gather data on the biological effects and the systemic toxicity of a novel medical device (Réjuve/IDSD) in the intervertebral discs (IVDs) of sheep. Gross and histological effects were compared between device-treated and sham-treated IVDs at 7 (+/-1), 28 (+/-1) and 84 (+/-3) days post-treatment. Systemic effects of device-treated sheep were also evaluated at the same time points.

A total of 26 animals were used in this study and divided in the following 5 cohorts: (1) acute/7-day (n=6; 7 ± 1 days), (2) sub-acute/28-day (n =6; 281 ± 1 days), (3) sub-chronic/84-day (n =6; 84 ± 3 days), (4) 7-day implantation effects (n = 4; 7±1 days) and (5) 28-day implantation effects (n=4; 28±1 days).

The acute/sub-acute/sub-chronic cohorts included 2 sham/control and 4 test-treated animals with equal gender distribution, totaling 18 animals. These cohorts were intended mainly to gather toxicity data. To ensure that both test and control animals undergo a similar number of lumbar IVD implants/treatments, 3 lumbar IVDs per animal were treated at Day 0. The sham/control-treated animals received 3 control/sham-treatments while the test animals received 2 Réjuve/IDSD IVD treatments and 1 sham/control treatment, resulting in a total of 18 treated IVDs per cohort. The IVD treatment assignments were randomized to reduce bias as much as possible during the evaluations.

Additionally, the 7-day implantation effects and 28-day implantation effects cohorts consisted of a total of 8 animals (n = 4 per cohort) and intended to gather data for the implantation effects including gross evaluation, histopathology of test and sham-treated sites as well as the general clinical health of the animals. Each animal from these 2 cohorts had 2 IVDs control/sham-treated and 2 IVDs Réjuve/test treated, resulting in a total of 8 treated IVDs per cohort. Each IVD treatment consisted of 2 injections of either Réjuve/test or sham/control per assigned IVD in all 5 study cohorts.

 Animals were weighed prior to the implant procedure and then regularly in the post-operative period. Animal daily observations as well as periodic physical examinations were performed to assess the general animal health. Blood and urine samples were collected for clinical pathology prior to treatment (baseline) and then prior to termination. All animals were euthanized at the end of the study duration according to the cohort assignments and had full necropsy performed by the Gross Pathology PI. Selected organs of the acute sub-acute and sub-chronic cohort animals were weighed. With the exception of the acute/7-day cohort, 7-day implantation effects and 28-day implantation effects animals, non-target organs/tissues were harvested. For all cohorts, any abnormal findings were documented and organs/tissues harvested. The test and control/sham IVD-treated sites of both implantation effects cohorts (i.e., 7-day and 28-day implantation effects) as well as the sub-chronic/84-day cohorts were grossly assessed. The harvested treated IVDs, non-target and abnormal organs/tissues were fixed with normal-buffered formalin (NBF) and submitted to the Histopathology site for processing and slide preparation. Histopathological evaluations of the Réjuve/test and sham/control-treated IVDs in addition to the non-target and abnormal organs/tissues were performed by the Histopathology PI.

 Results and Conclusions:

All of the objectives of this study to evaluate and gather data on the biological effects and the systemic toxicity of Réjuve implantation in the IVDs of sheep in comparison to sham-treatments were successfully met.

  • There were no major complications noted during the IVD treatment procedures as assessed by the Interventionalist.
  • There was no mortality. All animals were in good clinical health through the study duration. With the exception of a few animals of the 7-day cohorts, all animals either maintained or gained weight as expected. Some animals (test and control) of the 7-day cohorts lost weight during the short study duration, possibly because these animals did not have sufficient time while in the study to recover after the acclimation to the facility as well as the pre-operative fasts and immediate post-operatory effects. The lack of weight gain in the 7-day cohort was unrelated to the Test Article.
  • Multiple animals had evidence of localized inflammation at the treatment /injection sites, potentially due to a local reaction to the puncture and/or treatment, but unrelated to the Test Article.
  • All the hematology, serum chemistry and coagulation parameters (PT and APTT) findings were minor and not clinically relevant. There was no trending identified and the findings were unrelated to the Test Article.
  • None of the urinalysis findings were considered clinically significant and there was no evidence that the noted urinalysis abnormalities were related to the Test Article.
  • There were no effects of the Test Article on non-target organs. All gross lesions observed in nontarget organs at each time point were consistent with incidental findings not related to the Test Article. The results of the gross evaluation, histopathological analysis, clinical pathology, and in-life physical examinations were congruent with these lesions being incidental, background findings not related to the Test Article. All microscopic findings and all other macroscopic findings were incidental.
  • IVD injection with Réjuve led to diffuse blue discoloration of the IVD (annulus and nucleus pulposus). There was no inflammation, encapsulation, hemorrhage or necrosis based on the gross evaluations of the treated IVDs of all cohorts.
  • Evaluation of cranial/caudal midline sagittal sections through the IVD demonstrated no microscopic findings. The test article was considered a non-irritant as compared to the control article, as all sections evaluated shared a Total Irritancy score of 0.

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