Adipose-derived stem cells significantly increases collagen level and fiber maturity in patient-specific biological engineered blood vessels.

Tissue engineering has driven significant research in the strive to create a supply of tissues for patient treatment. Cell integration into engineered tissues maximizes functional capabilities, however, issues of rejection remain. Autologous cell sources able to solve this issue are difficult to identify for tissue engineering purposes. Here, we present the efficacy of patient-sourced cells derived from adipose (adipose-derived stem cells, ASCs) and skin tissue (dermal fibroblasts, PtFibs) to build a combined engineered tunica media and adventitia graft, respectively. Patient cells were integrated into our lab's vascular tissue engineering technique of forming vascular rings that are stacked into a tubular structure to create the vascular graft. For the media layer, ASCs were successfully differentiated into the smooth muscle phenotype using angiotensin II followed by culture in smooth muscle growth factors, evidenced by significantly increased expression of αSMA and myosin light chain kinase. Engineered media vessels composed of differentiated ASCs (ASC-SMCs) exhibited an elastic modulus (45.2 ± 18.9 kPa) between that of vessels of undifferentiated ASCs (71.8 ± 35.3 kPa) and control human aortic smooth muscle cells (HASMCs; 18.7 ± 5.49 kPa) (p<0.5). Tensile strength of vessels composed of ASCs (41.3 ± 15.7 kPa) and ASC-SMCs (37.3 ± 17.0 kPa) were higher compared to vessels of HASMCs (28.4 ± 11.2 kPa). ASC-based tissues exhibited a significant increase in collagen content and fiber maturity- both factors contribute to tissue strength and stability. Furthermore, vessels gained stability and a more-uniform single-tubular shape with longer-term 1-month culture. This work demonstrates efficacy of ASCs and PtFibs to create patient-specific vessels.

Porcine Acellular Peritoneal Matrix in Immediate Breast Reconstruction: A Multicenter, Prospective, Single-Arm Trial.

BACKGROUND: Use of biological implants such as acellular dermal matrices in tissue expander breast reconstruction is a common adjunct to submuscular implant placement. There is a paucity of published prospective studies involving acellular matrices. The authors sought to evaluate a porcine-derived acellular peritoneal matrix product for immediate breast reconstruction. METHODS: A prospective, single-arm trial was designed to analyze safety and outcomes of immediate tissue expander-based breast reconstruction with a novel porcine-derived acellular peritoneal matrix surgical mesh implant. Twenty-five patients were enrolled in this industry-sponsored trial. Patient demographics, surgical information, complications, histologic characteristics, and satisfaction (assessed by means of the BREAST-Q questionnaire) were evaluated. RESULTS: Twenty-five patients (44 breasts) underwent mastectomy with immediate breast reconstruction using tissue expanders with acellular peritoneal matrix. Sixteen reconstructed breasts experienced at least one complication (36 percent). Seroma and hematoma occurred in one of 44 (2.3 percent) and two of 44 breasts (4.6 percent), respectively. Wound dehiscence occurred in four of 44 breasts (9.1 percent). Three subjects experienced reconstruction failure resulting in expander and/or acellular peritoneal matrix removal (6.8 percent); all failures were preceded by wound dehiscence. Histologic analysis showed cellular infiltration and product resorption. Results of the BREAST-Q demonstrated a level of postoperative patient satisfaction consistent with results in the available literature. CONCLUSIONS: Prepared porcine-derived acellular peritoneal matrix is a safe adjunct in immediate two-stage tissue expander-based breast reconstruction. Further studies are required to determine efficacy compared to current commercially available acellular matrices. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Mechanical Stimulation Increases Knee Meniscus Gene RNA-level Expression in Adipose-derived Stromal Cells.

Efforts have been made to engineer knee meniscus tissue for injury repair, yet most attempts have been unsuccessful. Creating a cell source that resembles the complex, heterogeneous phenotype of the meniscus cell remains difficult. Stem cell differentiation has been investigated, mainly using bone marrow mesenchymal cells and biochemical means for differentiation, resulting in no solution. Mechanical stimulation has been investigated to an extent with no conclusion. Here, we explore the potential for and effectiveness of mechanical stimulation to induce the meniscal phenotype in adipose-derived stromal cells. METHODS: Human adipose-derived stromal cells were chosen for their fibrogenic nature and conduciveness for chondrogenesis. Biochemical and mechanical stimulation were investigated. Biochemical stimulation included fibrogenic and chondrogenic media. For mechanical stimulation, a custom-built device was used to apply constant, cyclical, uniaxial strain for up to 6 hours. Strain and frequency varied. RESULTS: Under biochemical stimulation, both fibrogenic (collagen I, versican) and chondrogenic (collagen II, Sox9, aggrecan) genes were expressed by cells exposed to either fibrogenic or chondrogenic biochemical factors. Mechanical strain was found to preferentially promote fibrogenesis over chondrogenesis, confirming that tensile strain is an effective fibrogenic cue. Three hours at 10% strain and 1 Hz in chondrogenic media resulted in the highest expression of fibrochondrogenic genes. Although mechanical stimulation did not seem to affect protein level expression, biochemical means did affect protein level presence of collagen fibers. CONCLUSION: Mechanical stimulation can be a useful differentiation tool for mechanoresponsive cell types as long as biochemical factors are also integrated.