Cecilia G. Sanchez

Cellulose nanofibrils (CNFs) and TEMPO-oxidized cellulose nanofibrils (TOCNFs) are hydrated, high-aspect-ratio biomaterials with tunable physicochemical properties, whereas human-derived extracellular matrix (ECM) hydrogels provide matrix-associated biochemical cues. In this study, CNF- and TOCNF-based hybrid scaffolds incorporating human ECM hydrogel components were developed and evaluated in vitro as platforms relevant to cutaneous wound repair. Hybrid formulations gelled at physiological temperature and exhibited formulation-dependent shear-thinning behavior, elastic properties, protein release/leaching profiles, and porous fibrillar microstructures. Selected formulations supported cell-associated metabolic activity of human dermal fibroblasts and adipose-derived stromal/stem cells under two-dimensional and three-dimensional culture conditions. Additional exploratory studies demonstrated qualitative compatibility with adipogenic culture and condition-dependent changes in wound-gap width. In the absence of in vivo validation and confirmatory biological assays, these findings are interpreted as proof-of-concept rather than evidence of wound-healing efficacy. Overall, the results demonstrate the feasibility of combining CNF or TOCNF structural networks with human-derived ECM hydrogels to generate hybrid scaffolds with wound-relevant material properties and preliminary cytocompatibility, supporting further mechanistic and preclinical evaluation.

Adipose tissue is recognized not only as an endocrine organ but also as a reservoir for adipose-derived stromal/stem cells (ASCs). ASCs have stimulated the interest of both the scientific and medical communities due to their therapeutic potential and applications in tissue engineering and regenerative medicine. ASCs are leveraged for their multipotency and their paracrine function. ASC behavior is highly variable and donor dependent. Donor age, body mass index, disease status, sex, and ethnicity can lead to differential overall function and quality. The impact of donor age and passage on ASC behavior has been well documented, impacting cell proliferation and differentiation potential and thus must be taken into careful consideration when conducting in vitro studies. Pooling of ASCs from different donors reduces heterogeneity among individual donors and produces ASCs with a consistent differentiation and paracrine profiles, an advantage for studies in biological aging. This chapter provides a detailed overview for studies related to quality control for ASC pools considering biological and chronological aging in ASCs. There are hallmarks of biological aging and specific assays associated with the evaluation of each hallmark. Nevertheless, here we present the assays that provide a standardized characterization and qualification of donor pools for their regenerative potential, considering chronological and biological age of the pool. The assays included in this chapter are considered quality control standards to evaluate cell proliferation, differentiation, colony-forming units, and cellular senescence from different donor age and cell passage cohorts.

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.

Hydrogels are 3D scaffolds used as alternatives to in vivo models for disease modeling and delivery of cells and drugs. Existing hydrogel classifications include synthetic, recombinant, chemically defined, plant‐ or animal‐based, and tissue‐derived matrices. There is a need for materials that can support both human tissue modeling and clinically relevant applications requiring stiffness tunability. Human‐derived hydrogels are not only clinically relevant, but they also minimize the use of animal models for pre‐clinical studies. This study aims to characterize XGel, a new human‐derived hydrogel as an alternative to current murine‐derived and synthetic recombinant hydrogels that features unique physiochemical, biochemical, and biological properties that support adipocyte and bone differentiation. Rheology studies determine the viscosity, stiffness, and gelation features of XGel. Quantitative studies for quality control support consistency in the protein content between lots. Proteomics studies reveal that XGel is predominantly composed of extracellular matrix proteins, including fibrillin, collagens I–VI, and fibronectin. Electron microscopy of the hydrogel provides phenotypic characteristics in terms of porosity and fiber size. The hydrogel demonstrates biocompatibility as a coating material and as a 3D scaffold for the growth of multiple cell types. The results provide insight into the biological compatibility of this human‐derived hydrogel for tissue engineering.