Preliminary results of tissue‐engineered injection laryngoplasty material in a rabbit model

Abstract

Objectives/Hypothesis: Design and test a novel biomaterial for injection laryngoplasty aimed to increase the duration of effectiveness of micronized acellular dermis.Study Design: Animal model. Methods: Injection laryngoplasty was performed in three groups (n 5 5) of New Zealand White rabbits. Acellular dermis was either used alone as a control (group 1), was combined with undifferentiated stem cells (group 2), or with predifferentiated chondrocytic cells (group 3). Groups 2 and 3 were supplemented with growth factors. Animals were sacrificed 4 and 12 weeks after laryngoplasty and histologic analysis was completed. The major outcome measure was volume of tissue remaining.Results: After 4 weeks, the mean volume of tissue remaining was 341 6 89 mm 3 , 295 6 102 mm 3 , and 133 6 15 mm 3 , for groups 1 to 3, respectively. At the 12-week time point, volumes were 62 6 62 mm 3 , 235 6 35 mm 3 , and 107 6 99 mm 3 . After 12 weeks, there was a significantly higher volume in group 2 compared to group 1 or 3 (P 5 .01, P 5 .04). Volumes between week 4 and week 12 were significantly lower in group 1 (P 5 .02), but not significantly different for groups 2 and 3 (P 5 .38, P 5 .74). Histologic evaluation revealed a robust lymphocytic infiltration in all cases as well as morphologic and immunophenotypic features suggestive of chondrogenic differentiation in a single animal.Conclusions: Micronized acellular dermis combined with stem cells and growth factors showed significantly less resorption 12 weeks after injection laryngoplasty compared to micronized acellular dermis alone. Groups using novel tissue-engineered biomaterial showed a lower resorption rate over time compared with acellular dermis alone.

Histone Variants as Stem Cell Biomarkers for Long‐Term Injection Medialization Laryngoplasty

“…Of these, 147 (MACD), 1,243 (MACD+ADSC), and 1,033 (MACD+CHON (chondrocytes[s])) proteins were validated by two or more unique peptides. We hypothesized that proliferation of injected ADSCs accounted primarily for the volume difference previously reported and sought to identify proteins uniquely present in the MACD+ADSC group. A total of 333 unique proteins were identified by Venn subtraction analysis in this group (Fig.…”

“…Our previous works suggests that this may not be the case. After 4 weeks, the mean volume of tissue remaining in the MACD+ADSC group was 295 ± 102 mm, whereas at 12 weeks it was 235 ± 35 mm, representing a ∼20% tissue loss . Thus, the volume of the implanted biomaterial is decreasing rather than increasing.…”

“…In previous work, we tested the efficacy of a MACD+ADSCs bioreagent for promoting VF medialization post RLN sectioning. We noted that compared to MACD alone, a medialization promoting volume three times larger was observed in the MACD+ADSC group at 12 weeks postinjection . Here, we focus on protein biomarkers of ADSC proliferation associated with the increased ellipsoid volume that correlate with the duration of clinical benefit.…”

“…All animal experiments were performed in agreement with the Guide for the Care and Use of Laboratory Animals and the U.S. Public Health Service's Policy on Humane Care and Use of Laboratory Animals. Procedures for animal surgery, IML, tissue fixation and embedding, sectioning, and staining were previously described . Briefly, 12 weeks post‐IML rabbits were sacrificed, their larynges collected and fixed in 10% formaldehyde for 24 hours or more.…”

“…To distinguish exogenous from endogenous cells, injected stem cells have been labeled, but dyes and biologicals are rapidly extruded and the signal fades within days. We previously showed that a combination of micronized acellular dermis (MACD) and adipose mesenchymal stem cells (ADSCs) increased long‐term IML medialization volume . We hypothesized that continued in vivo proliferation of ADSCs was mostly responsible for these results, but inflammatory processes may have also played a part.…”