In vitro formation and extended culture of highly metabolically active and contractile tissues.

3D cell culture models have gained popularity in recent years as an alternative to animal and 2D cell culture models for pharmaceutical testing and disease modeling. Polydimethylsiloxane (PDMS) is a cost-effective and accessible molding material for 3D cultures; however, routine PDMS molding may not be appropriate for extended culture of contractile and metabolically active tissues. Failures can include loss of culture adhesion to the PDMS mold and limited culture surfaces for nutrient and waste diffusion. In this study, we evaluated PDMS molding materials and surface treatments for highly contractile and metabolically active 3D cell cultures. PDMS functionalized with polydopamine allowed for extended culture duration (14.8 ± 3.97 days) when compared to polyethylamine/glutaraldehyde functionalization (6.94 ± 2.74 days); Additionally, porous PDMS extended culture duration (16.7 ± 3.51 days) compared to smooth PDMS (6.33 ± 2.05 days) after treatment with TGF-ß2 to increase culture contraction. Porous PDMS additionally allowed for large (13 mm tall × 8 mm diameter) constructs to be fed by diffusion through the mold, resulting in increased cell density (0.0210 ± 0.0049 mean nuclear fraction) compared to controls (0.0045 ± 0.0016 mean nuclear fraction). As a practical demonstration of the flexibility of porous PDMS, we engineered a vascular bioartificial muscle model (VBAM) and demonstrated extended culture of VBAMs anchored with porous PDMS posts. Using this model, we assessed the effect of feeding frequency on VBAM cellularity. Feeding 3×/week significantly increased nuclear fraction at multiple tissue depths relative to 2×/day. VBAM maturation was similarly improved in 3×/week feeding as measured by nuclear alignment (23.49° ± 3.644) and nuclear aspect ratio (2.274 ± 0.0643) relative to 2x/day (35.93° ± 2.942) and (1.371 ± 0.1127), respectively. The described techniques are designed to be simple and easy to implement with minimal training or expense, improving access to dense and/or metabolically active 3D cell culture models.

Organotypic cultures as aging associated disease models.

Aging remains a primary risk factor for a host of diseases, including leading causes of death. Aging and associated diseases are inherently multifactorial, with numerous contributing factors and phenotypes at the molecular, cellular, tissue, and organismal scales. Despite the complexity of aging phenomena, models currently used in aging research possess limitations. Frequently used in vivo models often have important physiological differences, age at different rates, or are genetically engineered to match late disease phenotypes rather than early causes. Conversely, routinely used in vitro models lack the complex tissue-scale and systemic cues that are disrupted in aging. To fill in gaps between in vivo and traditional in vitro models, researchers have increasingly been turning to organotypic models, which provide increased physiological relevance with the accessibility and control of in vitro context. While powerful tools, the development of these models is a field of its own, and many aging researchers may be unaware of recent progress in organotypic models, or hesitant to include these models in their own work. In this review, we describe recent progress in tissue engineering applied to organotypic models, highlighting examples explicitly linked to aging and associated disease, as well as examples of models that are relevant to aging. We specifically highlight progress made in skin, gut, and skeletal muscle, and describe how recently demonstrated models have been used for aging studies or similar phenotypes. Throughout, this review emphasizes the accessibility of these models and aims to provide a resource for researchers seeking to leverage these powerful tools.

Priming stroma with a vitamin D analog to optimize viroimmunotherapy for pancreatic cancer.

Pancreatic cancer resistance to immunotherapies is partly due to deficits in tumor-infiltrating immune cells and stromal density. Combination therapies that modify stroma and recruit immune cells are needed. Vitamin D analogs such as calcipotriol (Cal) decrease fibrosis in pancreas stroma, thus allowing increased chemotherapy delivery. OVs infect, replicate in, and kill cancer cells and recruit immune cells to immunodeficient microenvironments. We investigated whether stromal modification with Cal would enhance oncolytic viroimmunotherapy using recombinant orthopoxvirus, CF33. We assessed effect of Cal on CF33 replication using pancreas ductal adenocarcinoma (PDAC) cell lines and in vivo flank orthotopic models. Proliferation assays showed that Cal did not alter viral replication. Less replication was seen in cell lines whose division was slowed by Cal, but this appeared proportional to cell proliferation. Three-dimensional in vitro models demonstrated decreased myofibroblast integrity after Cal treatment. Cal increased vascular lumen size and immune cell infiltration in subcutaneous models of PDAC and increased viral delivery and replication. Cal plus serial OV dosing in the syngeneic Pan02 model caused more significant tumor abrogation than other treatments. Cal-treated tumors had less dense fibrosis, enhanced immune cell infiltration, and decreased T cell exhaustion. Calcipotriol is a possible adjunct for CF33-based oncolytic viroimmunotherapy against PDAC.