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

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) 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 ± 89 mm3 , 295 ± 102 mm3 , and 133 ± 15 mm3 , for groups 1 to 3, respectively. At the 12-week time point, volumes were 62 ± 62 mm3 , 235 ± 35 mm3 , and 107 ± 99 mm3 . After 12 weeks, there was a significantly higher volume in group 2 compared to group 1 or 3 (P = .01, P = .04). Volumes between week 4 and week 12 were significantly lower in group 1 (P = .02), but not significantly different for groups 2 and 3 (P = .38, P = .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. LEVEL OF EVIDENCE: NA. Laryngoscope, 128:160-167, 2018.

Histologic Evaluation of Micronized AlloDerm After Injection Laryngoplasty in a Rabbit Model.

OBJECTIVES/HYPOTHESIS: Micronized AlloDerm is a commonly used injectable material for injection laryngoplasty; however, the histologic response to laryngeal implantation and resorption rate over time have not been elucidated. This study aimed to evaluate the in vivo response of micronized AlloDerm over time after laryngeal implantation using a rabbit model. STUDY DESIGN: Animal model. METHODS: The left recurrent laryngeal nerve was sectioned in five New Zealand White rabbits to create a vocal cord paralysis. Two weeks later, injection laryngoplasty was performed with 100 µL of micronized AlloDerm. Animals were sacrificed 4 (two rabbits) and 12 (three rabbits) weeks after injection. Histologic sections were stained and evaluated by a single pathologist. Volume estimates were made by assuming the implant took an ellipsoid shape using dimensions calculated from histologic slides. RESULTS: In all cases, histological analysis revealed a lymphocytic inflammatory response infiltrating the peripheral margins of injection. After 4 weeks, the volume of injected material remaining in two rabbits was 404 and 278 mm3 (average 341 mm3 ). After 12 weeks, the volume of injected material remaining in three rabbits was 0, 61, and 124 mm3 (average 62 mm3 ), an 82% difference in volume of material between animals sacrificed at 4 weeks versus 12 weeks. CONCLUSIONS: Injection laryngoplasty using micronized AlloDerm induces a lymphocytic inflammatory response after injection in a rabbit model. Though a significant amount of material remains after 4 weeks, by 12 weeks the majority has been reabsorbed. LEVEL OF EVIDENCE: NA Laryngoscope, 127:E166-E169, 2017.

Adipose-Derived Mesenchymal Stem Cell Features in Patients with a History of Head and Neck Radiation.

OBJECTIVES/HYPOTHESIS: Radiation plays a prominent role in advanced stage head and neck tumors. Often, the radiated area includes adjacent nonmalignant mesenchymal tissue, which contains a mixture of cells that has been shown to accelerate wound healing. The purpose of this study is to determine the long-term effect of radiation on the expansion potential of adipose-derived stromal/stem cell (ADSC) tissue and on the ability of resident stem cells in this fraction to undergo phenotypic differentiation. Study Design/Methods: After institutional review board approval, 12 patients with a history of head and neck radiation and pending surgery were enrolled. Adipose tissue was collected from irradiated tissue (XRT) and nonirradiated tissue (NRT) sites. Mesenchymal stem cells were isolated from these populations, with subsequent assessment of cellular kinetics and differentiation potential between harvest sites. RESULTS: Adipose-derived stromal/stem cells could not be isolated from XRT in six patients due to lack of in vitro cell proliferation. For the remaining six patients, overall cumulative population-doubling time was longer for XRT relative to NRT (29.3 vs. 11.5 days; P = 0.02). However, no significant differences were observed in cell generation time or viability. When XRT and NRT ADSC fractions were grown to standardized concentrations and incubated under conditions that induce phenotypic differentiation of resident stem cells, no significant changes in chondrogenic, adipogenic, or osteogenic differentiation were observed. CONCLUSION: These preliminary observations suggest that irradiated ADSCs close to the surgical site undergo long-term changes in proliferative capacity. The potential for phenotypic differentiation is retained, however, in ADSCs that survive the irradiation process. LEVEL OF EVIDENCE: 2b.

Development and immunophenotyping of squamous cell carcinoma xenografts: tools for translational immunology.

OBJECTIVES/HYPOTHESIS: The objectives of this study were to delineate methods for the development of primary squamous cell carcinoma (SCCHN) xenografts and to define human leukocyte antigen (HLA), melanoma-associated antigen (MAGE)-A3, and human papilloma virus (HPV) 16 antigenic expression in resultant cellular products. STUDY DESIGN: Prospective experimental model. METHODS: Freshly isolated SCCHN xenografts were established in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice using a variety of methods. Resultant tumors were analyzed for expression patterns of HLA-A, MAGE-A3, and HPV 16. Appropriate controls were included to ensure the presence of human RNA. RESULTS: Three xenografts were successfully established and passaged in vivo. Characterization of the resultant products revealed that one was positive for HLA-A2 at both the DNA and protein levels. One of the tumor lines expressed MAGE-A3, whereas none expressed HPV 16. CONCLUSIONS: Freshly isolated SCCHN can be used to generate primary xenografts. Characterization of select patterns of protein expression in established xenografts is a precursor to the development of a mouse model for SCCHN using tumor bearing animals reconstituted with autologous patient leukocytes.