Clinical Evaluation of an Off-the-Shelf Allogeneic Adipose Matrix for Soft Tissue Reconstruction

Abstract

Biomaterials derived from human adipose extracellular matrix have shown promise in vitro and in animal studies as an off-the-shelf adipogenic matrix for sustained volume replacement. Herein, we report the results of a randomized prospective study conducted with allograft adipose matrix (AAM) grafted into the pannus of presurgical abdominoplasty patients 3 or 6 months before scheduled surgery. This is the first report of a longitudinal histologic analysis of AAM in clinical use.

Methods: Ten healthy patients undergoing elective abdominoplasty were recruited to receive AAM before surgery. Enrolled subjects were randomized into either a 3-month follow-up cohort or a 6-month follow-up cohort. Subjects were monitored for adverse events associated with AAM grafting in addition to undergoing serial biopsy. Following surgical excision of the pannus, representative samples from the AAM surgical sites were stained and evaluated with hematoxylin and eosin for tissue morphology, Masson's trichrome for collagen, and perilipin for adipocytes.

Results: All subjects tolerated AAM with no severe adverse events reported. At 3 months following implantation, AAM remained visible within the confines of the subjects' native surrounding adipose tissue with sparse adipocytes apparent within the matrix. By 6 months, AAM had remodeled and was primarily composed of perilipin-positive adipocytes. Histologic analysis confirmed tissue remodeling (hematoxylin and eosin), adipogenesis (perilipin), and angiogenesis (Masson's trichrome) occurred with the presence of AAM.

Conclusions: AAM is a safe, allogeneic, off-the-shelf regenerative matrix that is adipogenic and noninflammatory and promotes angiogenesis.

Fig. 1.

Clinical study enrollment and randomization design showing 16 enrolled subjects; of these, 10 met study inclusion criteria. Randomization into 1 of 2 cohorts occurred at the time of intervention yielding two cohorts, each with 5 subjects. Cohort 1 underwent abdominoplasty 3 months after intervention and cohort 2 at 6 months post intervention.

Fig. 2.

Abdominal wall grid utilized for injection.

Fig. 3.

Gross appearance of the AAM at 3 (A) and 6 (B) months.

Fig. 4.

Bivariate modeling of percent adipocyte coverage against time (months).

Fig. 5.

Bivariate modeling of the percent adipocyte coverage against present residual AAM.

Fig. 6.

Representative biopsy of AAM obtained at 1 month stained with Masson’s trichrome.

Fig. 7.

Representative biopsy of AAM obtained at 3 months stained with Masson’s trichrome.

Fig. 8.

Representative biopsy of AAM obtained at 2 months observed with immunohistochemistry for perilipin. Low magnification, 10X (left) with area of interest at high magnification, 40X (right).

Fig. 9.

Representative biopsy of AAM obtained at 3 months (A) or 6 months (B) observed with immunohistochemistry for perilipin.

Fig. 10.

Representative H&E staining across all time points. A, Injection site neighboring adipose tissue. B, One-month biopsy. C, Two-month biopsy. D, Tissue segment removed post panniculectomy at 3 months. E, Tissue segment removed post panniculectomy at 3 months.