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Despite its limitations, Ficoll® has remained the primary method of leukocyte isolation for decades due to a lack of viable alternatives. To address this, MicroMedicine has developed SorterraTM, an automated microfluidic system that enables highly consistent label-free white blood cell separation and concentration. In a comparative study, Sorterra recovered 25% more viable lymphocytes than Ficoll, 88 ± 7% and 69 ± 13%, respectively (n=48). Sorterra retained Sorterra and Ficoll isolates were assessed for B cell and T cell functionality. To assess B cells, the isolates were stimulated with R848 and IL-2 (n=9), and total IgG and IgM secretion were evaluated with ELISpot. Secretion from Sorterra and Ficoll isolates was shown to be equivalent using distribution free resampling analysis. To assess T cell functionality, negatively selected T cells from Sorterra and Ficoll isolates were activated with CD3/28 beads and expanded with IL-2 (n=12). The isolates displayed similar T cell activation (89±4% vs. 88±5% CD25+/CD69+), proliferation, and T cell phenotypes (Tn TCM, TEM, TEFF) at 7 and 10 days post activation. Compared to Ficoll, Sorterra enables rapid, automated isolation of leukocytes, consistently yielding more lymphocytes with negligible RBCs and platelet contamination while maintaining T cell and B cell function. By minimizing operator variability, Sorterra has the potential to transform cell separation by automating an outdated, variable, and labor-intensive process.

Although granulocyte signatures have been associated with SLE severity, their role in SLE has been poorly understood due to the suboptimal methods for granulocyte recovery from peripheral blood. An automated microfluidic technology (Sorterra™ prototype) was used to isolate all leukocytes with minimal platelet (PLT) or red blood cell (RBC) contamination to assess the cell subsets. Leukocytes were isolated from peripheral blood collected from healthy donors (HD) and SLE patients (3 female, 3 male in each group) using Sorterra, RBC lysis, or Ficoll®. Viability and recovery of each leukocyte subset was evaluated by cell counter and flow cytometry. Sorterra recovered 92±4% of leukocytes from HD and SLE samples with negligible RBC/PLT/microparticle (MP) contamination, whereas Ficoll isolated 35±15% of leukocytes, losing nearly all the granulocytes and retaining a substantial level of RBC/PLT/MP. With RBC lysis, up to 65% of neutrophils and 41% of eosinophils were lost in the process. Sorterra recovered more monocytes (~80%) than Ficoll (p The Sorterra prototype was superior to RBC lysis and Ficoll in recovering total leukocytes with high viability and ease of use and provided a more consistent leukocyte isolate from HD and SLE patients than other methods. The ability to recover granulocytes in their native state is unmatched by existing technologies and enables future studies to better elucidate the role of granulocytes in SLE development.

Macrophages (Mϕ) and dendritic cells (DCs) are critical antigen presenting cells that play pivotal roles in host responses to biomaterial implants. Although Mϕs have been widely studied for their roles in the inflammatory responses against biomaterials, the roles that DCs play in the host responses toward implanted materials have only recently been explored. DCs are of significant research interest because of the emergence of a large number of combination products that cross-traditional medical device boundaries. These products combine biomaterials with biologics, including cells, nucleic acids, and/or proteins. The biomaterial component may evoke an inflammatory response, primarily mediated by neutrophils and Mϕs, whereas the biologic component may elicit an immunogenic immune response, initiated by DCs involving lymphocyte activation. Control of Mϕ phenotypic balance from proinflammatory M1 to reparative M2 is a goal of investigators to optimize the host response to biomaterials. Similarly, control of DC phenotype from proinflammatory to toleragenic is of interest in vaccine delivery and tissue engineering/transplantation situations, respectively. This review discusses the interconnection between innate and adaptive immunity, the comparative and contrasting phenotypes and roles of Mϕs and DCs in immunity, their responses to biomaterials and the strategies to modulate their phenotype for applications in tissue engineering and vaccine delivery. Furthermore, the collaboration between and unique roles of DCs and Mϕs needs to be addressed in future studies to gain a more complete picture of host responses toward combination products.

A variety of combination products composed of biomaterials and biologics have been developed for tissue regeneration or vaccine delivery. The host immune response to the immunogenic biological components in such products may be modulated by the biomaterial component. Distinct biomaterials have been shown to differentially affect the maturation of dendritic cells (DCs). DCs are professional antigen-presenting cells (APCs) that bridge innate and adaptive immunity and play a central role in inducing immunity or initiating immune tolerance. However, the biomaterials systems used to study DC response thus far have been insufficient to draw a clear conclusion as to which biomaterial properties are the key to controlling DC phenotype. In this study, we developed a 96-well filter plate-based high-throughput (HTP) methodology to assess DC maturation upon biomaterial treatment. Equivalent biomaterial effects on DC phenotype were measured using the conventional flow cytometric and filter-plate method, which validated the HTP methodology. This methodology will be used to screen a large number of biomaterials simultaneously and to draw correlations between material properties and DC phenotype, thereby providing biomaterial design criteria and immunomodulatory strategies for both tissue engineering and vaccine delivery applications.

Porous silicon multilayer structures have remarkable optical and morphological properties that can be exploited for biosensing. In particular, a high internal surface area (>100 m(2)/cm(3)) and a linear response profile to changes in the dielectric environment enable fabrication of sensitive devices and a straightforward quantitation of the optical response. These essential operating characteristics are illustrated for p+ mesoporous silicon (pore diameter 15-20 nm) optical microcavities. A series of devices were prepared to permit the immobilization of glutathione-S-transferase ( approximately 50 kDa) within the porous matrix. Enzyme activity was exploited as an indirect means to quantitate the amount of protein immobilized. Activity was positively correlated with the optical sensor response. However, at high enzyme load the activity becomes nonlinear while the microcavity response remains linear. These data were used to determine the transduction limit (minimum amount of protein required to transduce an optical response), which is reported as areal mass sensitivity ranging between 50 and 250 pg/mm(2). This value is considered in context with the dynamic range of the bulk sensitivity, defined as the magnitude of the wavelength shift per refractive index unit, which was measured as a function of microcavity design parameters. This work has uncovered key parameters that can be tuned to improve the detection limit of this sensor modality. Because of the ever increasing number of emerging new biosensor technologies, defining sensor detection limits has become an ambiguous topic and a need exists to standardize measurements and sensitivity units. For chip-based devices, it seems appropriate to report sensitivity in terms of the minimum number of grams of bound target per surface area.

Dendritic cells (DCs) play a critical role in orchestrating the host responses to a wide variety of foreign antigens and are essential in maintaining immune tolerance. Distinct biomaterials have been shown to differentially affect the phenotype of DCs, which suggested that biomaterials may be used to modulate immune response toward the biologic component in combination products. The elucidation of biomaterial property-DC phenotype relationships is expected to inform rational design of immuno-modulatory biomaterials. In this study, DC response to a set of 12 polymethacrylates (pMAs) was assessed in terms of surface marker expression and cytokine profile. Principal component analysis (PCA) determined that surface carbon correlated with enhanced DC maturation, while surface oxygen was associated with an immature DC phenotype. Partial square linear regression, a multivariate modeling approach, was implemented and successfully predicted biomaterial-induced DC phenotype in terms of surface marker expression from biomaterial properties with R prediction 2 = 0.76. Furthermore, prediction of DC phenotype was effective based on only theoretical chemical composition of the bulk polymers with R prediction 2 = 0.80. These results demonstrated that immune cell response can be predicted from biomaterial properties, and computational models will expedite future biomaterial design and selection.

Dendritic cells (DCs) play pivotal roles in responding to foreign entities during the innate immune response and in initiating effective adaptive immunity as well as maintaining immune tolerance. The sensitivity of DCs to foreign stimuli also makes them useful cells to assess the inflammatory response to biomaterials. Elucidating material property-DC phenotype relationships using a well-defined biomaterial system is expected to provide criteria for immunomodulatory biomaterial design. Clinical titanium (Ti) substrates, including pretreatment (PT), sand blasted and acid etched (SLA), and modified SLA (modSLA), with different roughnesses and surface energies were used to treat DCs and resulted in differential DC responses. PT and SLA induced a mature DC (mDC) phenotype, while modSLA promoted a non-inflammatory environment by supporting an immature DC (iDC) phenotype, based on surface marker expression, cytokine production profiles and cell morphology. Principal component analysis (PCA) confirmed these experimental results, and also indicated that the non-stimulating property of modSLA covaried with certain surface properties, such as high surface hydrophilicity, percent oxygen and percent Ti of the substrates. In addition to previous research that demonstrated superior osteogenic properties of modSLA compared with PT and SLA, the results reported herein indicates that modSLA may further benefit implant osteointegration by reducing local inflammation and its associated osteoclastogenesis.