The differentiation and growth of adult stem cells within engineered tissue constructs are hypothesized to be influenced by cell-biomaterial interactions. In this study, we compared the chondrogenic ...differentiation of human adipose-derived adult stem (
hADAS) cells seeded in alginate and agarose hydrogels, and porous gelatin scaffolds (Surgifoam), as well as the functional properties of tissue engineered cartilage constructs. Chondrogenic media containing transforming growth factor beta 1 significantly increased the rates of protein and proteoglycan synthesis as well as the content of DNA, sulfated glycosaminoglycans, and hydroxyproline of engineered constructs as compared to control conditions. Furthermore, chondrogenic culture conditions resulted in 86%, and 160% increases (
p<0.05) in the equilibrium compressive and shear moduli of the gelatin scaffolds, although they did not affect the mechanical properties of the hydrogels over 28 days in culture. Cells encapsulated in the hydrogels exhibited a spherical cellular morphology, while cells in the gelatin scaffolds showed a more polygonal shape; however, this difference did not appear to hinder the chondrogenic differentiation of the cells. Furthermore, the equilibrium compressive and shear moduli of the gelatin scaffolds were comparable to agarose by day 28. Our results also indicated that increases in the shear moduli were significantly associated with increases in S-GAG content (
R
2=0.36,
p<0.05) and with the interaction between S-GAG and hydroxyproline (
R
2=0.34,
p<0.05). The findings of this study suggest that various biomaterials support the chondrogenic differentiation of
hADAS cells, and that manipulating the composition of these tissue engineered constructs may have significant effects on their mechanical properties.
Abstract Biomaterials derived from silk fibroin prepared by aqueous (AB) and organic (HFIP) solvent-based processes, along with collagen (COL) and poly-lactic acid (PLA)-based scaffolds were studied ...in vitro and in vivo for their utility in adipose tissue engineering strategies. For in vitro studies, human bone marrow and adipose-derived mesenchymal stem cells (hMSCs and hASCs) were seeded on the various biomaterials and cultured for 21 days in the presence of adipogenic stimulants (AD) or maintained as noninduced controls. Alamar Blue analysis revealed each biomaterial supported initial attachment of hMSCs and hASCs to similar levels for all matrices except COL in which higher levels were observed. hASCs and hMSCs cultured on all biomaterials in the presence of AD showed significant upregulation of adipogenic mRNA transcript levels (LPL, GLUT4, FABP4, PPAR γ , adipsin, ACS) to similar extents when compared to noninduced controls. Similarly Oil-Red O analysis of hASC or hMSC-seeded scaffolds displayed substantial amounts of lipid accumulating adipocytes following cultivation with AD. The data revealed AB and HFIP scaffolds supported similar extents of lipid accumulating cells while PLA and COL scaffolds qualitatively displayed lower and higher extents by comparison, respectively. Following a 4-week implantation period in a rat muscle pouch defect model, both AB and HFIP scaffolds supported in vivo adipogenesis either alone or seeded with hASCs or hMSCs as assessed by Oil-Red O analysis, however the presence of exogenous cell sources substantially increased the extent and frequency of adipogenesis observed. In contrast, COL and PLA scaffolds underwent rapid scaffold degradation and were irretrievable following the implantation period. The results suggest that macroporous 3D AB and HFIP silk fibroin scaffolds offer an important platform for cell-based adipose tissue engineering applications, and in particular, provide longer-term structural integrity to promote the maintenance of soft tissue in vivo.
Hydrogels are considered a viable in vitro alternative to monolayer cultures. They provide quintessential characteristics for in vitro studies including biocompatibility, biodegradability, ...viscoelasticity, hydrophilicity, and low toxicity. Furthermore, many provide necessary extracellular matrix proteins and architecture to support cell growth, proliferation, differentiation, and migration. Synthetic and natural polymer-derived hydrogels both demonstrate positive qualities; however, natural hydrogels have attracted great interest due to their clinical relevancy. In particular, decellularized tissue-derived hydrogels have been identified as a significant resource for tissue engineering applications by mimicking the composition and architecture of their tissue of origin.The use of adipose tissue as a hydrogel has become more prevalent because of limitless resources and accessibility of the tissue itself. Obatala Sciences has established a manufacturing protocol for human decellularized adipose tissue (hDAT) using a series of steps including mechanical disruption, chemical disruption with N-Lauroylsarcosine, and enzymatic digestion with pepsin and hydrochloric acid.
Background
Cell-based therapies such as tissue engineering provide promising therapeutic possibilities to enhance the repair or regeneration of damaged or diseased tissues but are dependent on the ...availability and controlled manipulation of appropriate cell sources.
Questions/purposes
The goal of this study was to test the hypothesis that adult subcutaneous fat contains stem cells with multilineage potential and to determine the influence of specific soluble mediators and biomaterial scaffolds on their differentiation into musculoskeletal phenotypes.
Methods
We reviewed recent studies showing the stem-like characteristics and multipotency of adipose-derived stem cells (ASCs), and their potential application in cell-based therapies in orthopaedics.
Results
Under controlled conditions, ASCs show phenotypic characteristics of various cell types, including chondrocytes, osteoblasts, adipocytes, neuronal cells, or muscle cells. In particular, the chondrogenic differentiation of ASCs can be induced by low oxygen tension, growth factors such as bone morphogenetic protein-6 (BMP-6), or biomaterial scaffolds consisting of native tissue matrices derived from cartilage. Finally, focus is given to the development of a functional biomaterial scaffold that can provide ASC-based constructs with mechanical properties similar to native cartilage.
Conclusions
Adipose tissue contains an abundant source of multipotent progenitor cells. These cells show cell surface marker profiles and differentiation characteristics that are similar to but distinct from other adult stem cells, such as bone marrow mesenchymal stem cells (MSCs).
Clinical Relevance
The availability of an easily accessible and reproducible cell source may greatly facilitate the development of new cell-based therapies for regenerative medicine applications in the musculoskeletal system.
Female breast cancer accounts for 15.2% of all new cancer cases in the United States, with a continuing increase in incidence despite efforts to discover new targeted therapies. With an approximate ...failure rate of 85% for therapies in the early phases of clinical trials, there is a need for more translatable, new preclinical in vitro models that include cellular heterogeneity, extracellular matrix, and human-derived biomaterials. Specifically, adipose tissue and its resident cell populations have been identified as necessary attributes for current preclinical models. Adipose-derived stromal/stem cells (ASCs) and mature adipocytes are a normal part of the breast tissue composition and not only contribute to normal breast physiology but also play a significant role in breast cancer pathophysiology. Given the recognized pro-tumorigenic role of adipocytes in tumor progression, there remains a need to enhance the complexity of current models and account for the contribution of the components that exist within the adipose stromal environment to breast tumorigenesis. This review article captures the current landscape of preclinical breast cancer models with a focus on breast cancer microphysiological system (MPS) models and their counterpart patient-derived xenograft (PDX) models to capture patient diversity as they relate to adipose tissue.
Articular cartilage exhibits little intrinsic repair capacity, and new tissue engineering approaches are being developed to promote cartilage regeneration using cellular therapies. The goal of this ...study was to examine the chondrogenic potential of adipose tissue-derived stromal cells. Stromal cells were isolated from human subcutaneous adipose tissue obtained by liposuction and were expanded and grown in vitro with or without chondrogenic media in alginate culture. Adipose-derived stromal cells abundantly synthesized cartilage matrix molecules including collagen type II, VI, and chondroitin 4-sulfate. Alginate cell constructs grown in chondrogenic media for 2 weeks in vitro were then implanted subcutaneously in nude mice for 4 and 12 weeks. Immunohistochemical analysis of these samples showed significant production of cartilage matrix molecules. These findings document the ability of adipose tissue-derived stromal cells to produce characteristic cartilage matrix molecules in both in vitro and in vivo models, and suggest the potential of these cells in cartilage tissue engineering.
The immunomodulatory properties of mesenchymal stem cells (MSCs) make them attractive therapeutic agents for a wide range of diseases. However, the highly demanding cell doses used in MSC clinical ...trials (up to millions of cells/kg patient) currently require labor intensive methods and incur high reagent costs. Moreover, the use of xenogenic (xeno) serum-containing media represents a risk of contamination and raises safety concerns. Bioreactor systems in combination with novel xeno-free medium formulations represent a viable alternative to reproducibly achieve a safe and reliable MSC doses relevant for cell therapy. The main goal of the present study was to develop a complete xeno-free microcarrier-based culture system for the efficient expansion of human MSC from two different sources, human bone marrow (BM), and adipose tissue. After 14 days of culture in spinner flasks, BM MSC reached a maximum cell density of (2.0±0.2)×10⁵ cells·mL⁻¹ (18±1-fold increase), whereas adipose tissue-derived stem cells expanded to (1.4±0.5)×10⁵ cells·mL⁻¹ (14±7-fold increase). After the expansion, MSC expressed the characteristic markers CD73, CD90, and CD105, whereas negative for CD80 and human leukocyte antigen (HLA)-DR. Expanded cells maintained the ability to differentiate robustly into osteoblast, adipocyte, and chondroblast lineages upon directed differentiation. These results demonstrated the feasibility of expanding human MSC in a scalable microcarrier-based stirred culture system under xeno-free conditions and represent an important step forward for the implementation of a Good Manufacturing Practices-compliant large-scale production system of MSC for cellular therapy.
Information relating to the biology, culture expansion, and mechanisms relating to adipose-derived cells has advanced significantly in the past decade. Both the heterogeneous stromal vascular ...fraction (SVF) and more homogeneous adipose-derived stem cells (ASC) offer unique opportunities as novel cell-based therapeutics and as traditional pharmaceutical discovery tools. This review highlights the cytokine secretory functions of ASC and SVF cells as well as their potential use as immunomodulators and gene delivery vehicles. These functions make it feasible to exploit adipose-derived cells in the treatment of ischemic, musculoskeletal, and oncological disorders. With appropriate commercial development and in vivo validation, ASC and SVF cells will have a significant therapeutic impact in the future.
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