Response of Rat Tibia to Prolonged Unloading Under the Influence of Electrical Stimulation at the Dorsal Root Ganglion.

PURPOSE: Immobilization of weight bearing skeletons or microgravity results in disuse osteoporosis in both human and animals. Our previous study demonstrated that electrical stimulation at the dorsal root ganglion (DRG) with an implantable micro-electrical stimulation system (IMESS) could trigger secretion of bone anabolic calcitonin gene-related peptide (CGRP) and prevent bone loss in a short-term hindlimb unloading rat model. This study was designed to further investigate whether electrical stimulation to the DRG could prevent bone loss due to prolonged unloading. METHODS: Eighteen adult rats were randomly assigned into three groups: cage control (CC), hindlimb unloading (HU), and hindlimb unloading with electrical stimulation (HUES). Electrical stimulation was applied via IMESS to the right DRGs at vertebral levels L4-L6 in HUES group for 6 weeks. RESULTS: Following unloading for 6 weeks, proximal tibia metaphysis was shown 64.0% decrease in bone mineral content (BMC) and 47.0% decrease in bone mineral density (BMD) in HU group while significant reduced bone lose with 2.7% increase in total BMC and only 9.2% decrease in total BMD in HUES group. Diaphyseal BMD decreased significantly in both HU and HUES group as compared with CC group. There was enhancement of CGRP expression in the DRGs in HUES group. CONCLUSION: This experimental study proved the proposed concept using electrical stimulation at the DRG for prevention of disuse-induced bone loss in a rat hindlimb suspension model.

Mesenchymal stem cells reduce intervertebral disc fibrosis and facilitate repair.

Intervertebral disc degeneration is associated with back pain and radiculopathy which, being a leading cause of disability, seriously affects the quality of life and presents a hefty burden to society. There is no effective intervention for the disease and the etiology remains unclear. Here, we show that disc degeneration exhibits features of fibrosis in humans and confirmed this in a puncture-induced disc degeneration (PDD) model in rabbit. Implantation of bone marrow-derived mesenchymal stem cells (MSCs) to PDD discs can inhibit fibrosis in the nucleus pulposus with effective preservation of mechanical properties and overall spinal function. We showed that the presence of MSCs can suppress abnormal deposition of collagen I in the nucleus pulposus, modulating profibrotic mediators MMP12 and HSP47, thus reducing collagen aggregation and maintaining proper fibrillar properties and function. As collagen fibrils can regulate progenitor cell activities, our finding provides new insight to the limited self-repair capability of the intervertebral disc and importantly the mechanism by which MSCs may potentiate tissue regeneration through regulating collagen fibrillogenesis in the context of fibrotic diseases.

Targeting stress induction of GRP78 by cardiac glycoside oleandrin dually suppresses cancer and COVID-19.

BACKGROUND: Despite recent therapeutic advances, combating cancer resistance remains a formidable challenge. The 78-kilodalton glucose-regulated protein (GRP78), a key stress-inducible endoplasmic reticulum (ER) chaperone, plays a crucial role in both cancer cell survival and stress adaptation. GRP78 is also upregulated during SARS-CoV-2 infection and acts as a critical host factor. Recently, we discovered cardiac glycosides (CGs) as novel suppressors of GRP78 stress induction through a high-throughput screen of clinically relevant compound libraries. This study aims to test the possibility that agents capable of blocking stress induction of GRP78 could dually suppress cancer and COVID-19. RESULTS: Here we report that oleandrin (OLN), is the most potent among the CGs in inhibiting acute stress induction of total GRP78, which also results in reduced cell surface and nuclear forms of GRP78 in stressed cells. The inhibition of stress induction of GRP78 is at the post-transcriptional level, independent of protein degradation and autophagy and may involve translational control as OLN blocks stress-induced loading of ribosomes onto GRP78 mRNAs. Moreover, the human Na+/K+-ATPase α3 isoform is critical for OLN suppression of GRP78 stress induction. OLN, in nanomolar range, enhances apoptosis, sensitizes colorectal cancer cells to chemotherapeutic agents, and reduces the viability of patient-derived colon cancer organoids. Likewise, OLN, suppresses GRP78 expression and impedes tumor growth in an orthotopic breast cancer xenograft model. Furthermore, OLN blocks infection by SARS-CoV-2 and its variants and enhances existing anti-viral therapies. Notably, GRP78 overexpression mitigates OLN-mediated cancer cell apoptotic onset and suppression of virus release. CONCLUSION: Our findings validate GRP78 as a target of OLN anti-cancer and anti-viral activities. These proof-of-principle studies support further investigation of OLN as a readily accessible compound to dually combat cancer and COVID-19.

Integration of Patient-Derived Organoids and Organ-on-Chip Systems: Investigating Colorectal Cancer Invasion within the Mechanical and GABAergic Tumor Microenvironment.

Three-dimensional (3D) in vitro models are essential in cancer research, but they often neglect physical forces. In our study, we combined patient-derived tumor organoids with a microfluidic organ-on-chip system to investigate colorectal cancer (CRC) invasion in the tumor microenvironment (TME). This allowed us to create patient-specific tumor models and assess the impact of physical forces on cancer biology. Our findings showed that the organoid-on-chip models more closely resembled patient tumors at the transcriptional level, surpassing organoids alone. Using 'omics' methods and live-cell imaging, we observed heightened responsiveness of KRAS mutant tumors to TME mechanical forces. These tumors also utilized the γ-aminobutyric acid (GABA) neurotransmitter as an energy source, increasing their invasiveness. This bioengineered model holds promise for advancing our understanding of cancer progression and improving CRC treatments.

Reprogramming CBX8-PRC1 function with a positive allosteric modulator.

Canonical targeting of Polycomb repressive complex 1 (PRC1) to repress developmental genes is mediated by cell-type-specific, paralogous chromobox (CBX) proteins (CBX2, 4, 6, 7, and 8). Based on their central role in silencing and their dysregulation associated with human disease including cancer, CBX proteins are attractive targets for small-molecule chemical probe development. Here, we have used a quantitative and target-specific cellular assay to discover a potent positive allosteric modulator (PAM) of CBX8. The PAM activity of UNC7040 antagonizes H3K27me3 binding by CBX8 while increasing interactions with nucleic acids. We show that treatment with UNC7040 leads to efficient and selective eviction of CBX8-containing PRC1 from chromatin, loss of silencing, and reduced proliferation across different cancer cell lines. Our discovery and characterization of UNC7040 not only reveals the most cellularly potent CBX8-specific chemical probe to date, but also corroborates a mechanism of Polycomb regulation by non-specific CBX nucleotide binding activity.

Imaging-Based Machine Learning Analysis of Patient-Derived Tumor Organoid Drug Response.

Three-quarters of compounds that enter clinical trials fail to make it to market due to safety or efficacy concerns. This statistic strongly suggests a need for better screening methods that result in improved translatability of compounds during the preclinical testing period. Patient-derived organoids have been touted as a promising 3D preclinical model system to impact the drug discovery pipeline, particularly in oncology. However, assessing drug efficacy in such models poses its own set of challenges, and traditional cell viability readouts fail to leverage some of the advantages that the organoid systems provide. Consequently, phenotypically evaluating complex 3D cell culture models remains difficult due to intra- and inter-patient organoid size differences, cellular heterogeneities, and temporal response dynamics. Here, we present an image-based high-content assay that provides object level information on 3D patient-derived tumor organoids without the need for vital dyes. Leveraging computer vision, we segment and define organoids as independent regions of interest and obtain morphometric and textural information per organoid. By acquiring brightfield images at different timepoints in a robust, non-destructive manner, we can track the dynamic response of individual organoids to various drugs. Furthermore, to simplify the analysis of the resulting large, complex data files, we developed a web-based data visualization tool, the Organoizer, that is available for public use. Our work demonstrates the feasibility and utility of using imaging, computer vision and machine learning to determine the vital status of individual patient-derived organoids without relying upon vital dyes, thus taking advantage of the characteristics offered by this preclinical model system.

Human colorectal cancer-on-chip model to study the microenvironmental influence on early metastatic spread.

Colorectal cancer (CRC) progression is a complex process that is not well understood. We describe an in vitro organ-on-chip model that emulates in vivo tissue structure and the tumor microenvironment (TME) to better understand intravasation, an early step in metastasis. The CRC-on-chip incorporates fluid flow and peristalsis-like cyclic stretching and consists of endothelial and epithelial compartments, separated by a porous membrane. On-chip imaging and effluent analyses are used to interrogate CRC progression and the resulting cellular heterogeneity. Mass spectrometry-based metabolite profiles are indicative of a CRC disease state. Tumor cells intravasate from the epithelial channel to the endothelial channel, revealing differences in invasion between aggressive and non-aggressive tumor cells. Tuning the TME by peristalsis-like mechanical forces, the epithelial:endothelial interface, and the addition of fibroblasts influences the invasive capabilities of tumor cells. The CRC-on-chip is a tunable human-relevant model system and a valuable tool to study early invasive events in cancer.

High-throughput microscopy reveals the impact of multifactorial environmental perturbations on colorectal cancer cell growth.

BACKGROUND: Colorectal cancer (CRC) mortality is principally due to metastatic disease, with the most frequent organ of metastasis being the liver. Biochemical and mechanical factors residing in the tumor microenvironment are considered to play a pivotal role in metastatic growth and response to therapy. However, it is difficult to study the tumor microenvironment systematically owing to a lack of fully controlled model systems that can be investigated in rigorous detail. RESULTS: We present a quantitative imaging dataset of CRC cell growth dynamics influenced by in vivo-mimicking conditions. They consist of tumor cells grown in various biochemical and biomechanical microenvironmental contexts. These contexts include varying oxygen and drug concentrations, and growth on conventional stiff plastic, softer matrices, and bioengineered acellular liver extracellular matrix. Growth rate analyses under these conditions were performed via the cell phenotype digitizer (CellPD). CONCLUSIONS: Our data indicate that the growth of highly aggressive HCT116 cells is affected by oxygen, substrate stiffness, and liver extracellular matrix. In addition, hypoxia has a protective effect against oxaliplatin-induced cytotoxicity on plastic and liver extracellular matrix. This expansive dataset of CRC cell growth measurements under in situ relevant environmental perturbations provides insights into critical tumor microenvironment features contributing to metastatic seeding and tumor growth. Such insights are essential to dynamical modeling and understanding the multicellular tumor-stroma dynamics that contribute to metastatic colonization. It also establishes a benchmark dataset for training and testing data-driven dynamical models of cancer cell lines and therapeutic response in a variety of microenvironmental conditions.

PD1 blockade reverses the suppression of melanoma antigen-specific CTL by CD4+ CD25(Hi) regulatory T cells.

Regulatory CD4(+)CD25(Hi) T cells (Treg) and programmed death-1 (PD-1) molecule have emerged as pivotal players in immune regulation. However, the underlying mechanisms by which they impact antigen-specific CD8(+) immune responses in cancer patients and how they interact with each other under physiologic conditions remain unclear. Herein, we examined the relationship of PD-1 and its abrogation to the function of Treg in patients with melanoma using short-term in vitro assays to generate melanoma-specific T cells. We identified Treg in the circulation of vaccinated melanoma patients and detected PD-1 expression on vaccine-induced melanoma antigen-specific CTLs, as well as on and within Treg from patients' peripheral blood. Programmed death ligand (PD-L) 1 expression was also detected on patients' Treg. PD-1 blockade promoted the generation of melanoma antigen-specific CTLs and masked their inhibition by Treg. The mechanisms by which PD-1 blockade mediated immune enhancement included direct augmentation of melanoma antigen-specific CTL proliferation, heightening their resistance to inhibition by Treg and direct limitation of the inhibitory ability of Treg. PD-1 blockade reversed the increased expression of PD-1 and PD-L1 on melanoma antigen-specific CTL by Treg, rescued INF-gamma and IL-2 or INF-gamma and tumor necrosis factor-alpha co-expression and expression of IL-7 receptor by melanoma antigen-specific CTL which were diminished by Treg. PD-1 blockade also resulted in down-regulation of intracellular FoxP3 expression by Treg. These data suggest that PD-1 is importantly implicated in the regulation of Treg function in melanoma patients.

Comparison of Cell and Organoid-Level Analysis of Patient-Derived 3D Organoids to Evaluate Tumor Cell Growth Dynamics and Drug Response.

3D cell culture models have been developed to better mimic the physiological environments that exist in human diseases. As such, these models are advantageous over traditional 2D cultures for screening drug compounds. However, the practicalities of transitioning from 2D to 3D drug treatment studies pose challenges with respect to analysis methods. Patient-derived tumor organoids (PDTOs) possess unique features given their heterogeneity in size, shape, and growth patterns. A detailed assessment of the length scale at which PDTOs should be evaluated (i.e., individual cell or organoid-level analysis) has not been done to our knowledge. Therefore, using dynamic confocal live cell imaging and data analysis methods we examined tumor cell growth rates and drug response behaviors in colorectal cancer (CRC) PDTOs. High-resolution imaging of H2B-GFP-labeled organoids with DRAQ7 vital dye permitted tracking of cellular changes, such as cell birth and death events, in individual organoids. From these same images, we measured morphological features of the 3D objects, including volume, sphericity, and ellipticity. Sphericity and ellipticity were used to evaluate intra- and interpatient tumor organoid heterogeneity. We found a strong correlation between organoid live cell number and volume. Linear growth rate calculations based on volume or live cell counts were used to determine differential responses to therapeutic interventions. We showed that this approach can detect different types of drug effects (cytotoxic vs cytostatic) in PDTO cultures. Overall, our imaging-based quantification workflow results in multiple parameters that can provide patient- and drug-specific information for screening applications.

Anti-EGFR Therapy Induces EGF Secretion by Cancer-Associated Fibroblasts to Confer Colorectal Cancer Chemoresistance.

Targeted agents have improved the efficacy of chemotherapy for cancer patients, however, there remains a lack of understanding of how these therapies affect the unsuspecting bystanders of the stromal microenvironment. Cetuximab, a monoclonal antibody therapy targeting the epidermal growth factor receptor (EGFR), is given in combination with chemotherapy as the standard of care for a subset of metastatic colorectal cancer patients. The overall response to this treatment is underwhelming and, while genetic mutations that confer resistance have been identified, it is still not known why this drug is ineffective for some patients. We discovered that cancer-associated fibroblasts (CAFs), a major cellular subset of the tumor stroma, can provide a source of cancer cell resistance. Specifically, we observed that upon treatment with cetuximab, CAFs increased their secretion of EGF, which was sufficient to render neighboring cancer cells resistant to cetuximab treatment through sustained mitogen-activated protein kinases (MAPK) signaling. Furthermore, we show the cetuximab-induced EGF secretion to be specific to CAFs and not to cancer cells or normal fibroblasts. Altogether, this work emphasizes the importance of the tumor microenvironment and considering the potential unintended consequences of therapeutically targeting cancer-driving proteins on non-tumorigenic cell types.

Post pressure response of skin blood flowmotions in anesthetized rats with spinal cord injury.

Pressure ulcer is a common complication developed in persons with spinal cord injury (SCI) when prolonged unrelieved pressure was applied to the body/skin and underlying tissues. The objective of this study is to assess the hyperemic response of the skin blood flowmotions in anesthetized rats with spinal cord injury subjected to prolonged pressure using spectral analysis based on wavelets transform of the periodic oscillations of the cutaneous laser Doppler flowmetry (LDF) signal. A total of twenty-eight Sprague-Dawley rats were used in this study, of which 14 were normal rats and the other 14 were spinal cord injured rats with transection of the T1 spinal nerves. External pressure of 13.3 kPa (100 mmHg) was applied to the trochanter area of rats via a specifically designed indentors. The loading duration was 6 h. LDF measurement was monitored for 20 min prior to and after the prescribed compression period. Five frequency intervals were identified (0.01-0.05 Hz, 0.05-0.15 Hz, 0.15-0.4 Hz, 0.4-2 Hz and 2-5 Hz) corresponding to endothelial related metabolic, neurogenic, myogenic, respiratory and cardiac origins. The absolute amplitude of oscillations of each particular frequency interval and the normalized amplitude were calculated for quantitative assessments. Comparisons of hyperemic response were performed between SCI rats and normal ones. The results showed that the normalized amplitude in the frequency interval II (0.05-0.15 Hz) was significantly lower on SCI rats than that in normal ones (p<0.01). Also, decreased reactive hyperemic response was observed in rats suffered from spinal cord injury.

The time effect of pressure on tissue viability: investigation using an experimental rat model.

An experimental rat model was used to investigate the time-pressure effect on tissue viability. External loading equivalent to 13.3 kPa (100 mm Hg) of pressure was applied to the greater trochanter and tibialis area of Sprague-Dawley rats using pneumatic indentors for duration of 6 hrs each day for 1 to 4 days. It was observed that postocclusive hyperemic responses were gradually increased at the trochanter throughout the 4 days of loading, whereas for the tibia there was a significant increase (P = 0.04) in postocclusive hyperemic flow between Days 2 and 3. In histologic evaluations, cutaneous tissue damage was observed at the trochanter area but not at the tibialis area after 2 consecutive days of load application. In contrast, degeneration of muscle cells characterized by numerous increases of nuclei occupying the central of the muscle fibers was observed after 2 days of load application at the tibialis. The situation was found to progress with time (P = 0.17). The presence of other histologic signs, including the internalization of peripherally located nuclei, replacement of muscle cells by fibrosis and adipose tissues, and the presence of pyknotic nuclei as well as karyorrhexis, confirmed that the affected tissues were damaged. These findings suggest that postocclusive hyperemia and the distress of tissues under loading could be closely related.

Wavelet analysis of the effects of static magnetic field on skin blood flowmotion: investigation using an in vivo rat model.

BACKGROUND: In the literature, various in vivo studies on animals have demonstrated that a static magnetic field (SMF) might maintain microvascular tone in the cutaneous microcirculatory system by its biphasic effects on vasomotion. Here, the effects of locally applied SMF on skin blood flowmotion within the stressed or unstressed skin in the trochanter area were evaluated using wavelet analysis of skin blood perfusion as measured by laser Doppler flowmetry (LDF) in anesthetized rats. MATERIALS AND METHODS: Forty-eight experimental trials were carried out on twelve Sprague-Dawley rats. Four experimental groups were formed at random: i) Group CNL (no loading or SMF exposure; n = 12 trials); ii) Group SMF (SMF exposure only; n = 12 trials); iii) Group L (stressed skin without SMF exposure; n = 12 trials); iv) Group L + SMF (stressed skin with SMF exposure; n = 12 trials). RESULTS: SMF significantly enhanced endothelial related metabolic activity (0.01-0.05 Hz) in the stressed skin (p = 0.03). However, SMF did not induce significant change in the flowmotion amplitude in the unstressed skin (p = 0.22). CONCLUSION: The modulating effect of SMF on skin blood flowmotion might be related to the vascular tone modified by prolonged loading.

Effects of prolonged compression on the variations of haemoglobin oxygenation - assessment by spectral analysis of reflectance spectrophotometry signals.

The consequences of rhythmical flow motion for nutrition and the oxygen supply to tissue are largely unknown. In this study, the periodic variations of haemoglobin oxygenation in compressed and uncompressed skin were evaluated with a reflection spectrometer using an in vivo Sprague-Dawley rat model. Skin compression was induced over the trochanter area by a locally applied external pressure of 13.3 kPa (100 mmHg) via a specifically designed pneumatic indentor. A total of 19 rats were used in this study. The loading duration is 6 h per day for four consecutive days. Haemoglobin oxygenation variations were quantified using spectral analysis based on wavelets' transformation. The results found that in both compressed and uncompressed skin, periodic variations of the haemoglobin oxygenation were characterized by two frequencies in the range of 0.01-0.05 Hz and 0.15-0.4 Hz. These frequency ranges coincide with those of the frequency range of the endothelial-related metabolic and myogenic activities found in the flow motion respectively. Tissue compression following the above loading schedule induced a significant decrease in the spectral amplitudes of frequency interval 0.01-0.05 Hz during the pre-occlusion period on day 3 and day 4 as compared to that on day 1 (p < 0.05). In contrast, at a frequency range of 0.15-0.4 Hz, prolonged compression caused a significant increase in spectral amplitude during the pre-occlusion period in the compressed tissue on day 3 (p = 0.041) and day 4 (p = 0.024) compared to that in the uncompressed tissue on day 1. These suggested that the variations of the haemoglobin oxygenation were closely related to the endothelial-related metabolic and myogenic activities. Increased amplitude in the frequency interval 0.15-0.4 Hz indicated an increased workload of the vascular smooth muscle and could be attributed to the increase of O(2) consumption rates of arteriolar walls. The modification of vessel wall oxygen consumption might substantially affect the available oxygen supply to the compressed tissue. This mechanism might be involved in the process leading to pressure ulcer formation.

Quantifying differences in cell line population dynamics using CellPD.

BACKGROUND: The increased availability of high-throughput datasets has revealed a need for reproducible and accessible analyses which can quantitatively relate molecular changes to phenotypic behavior. Existing tools for quantitative analysis generally require expert knowledge. RESULTS: CellPD (cell phenotype digitizer) facilitates quantitative phenotype analysis, allowing users to fit mathematical models of cell population dynamics without specialized training. CellPD requires one input (a spreadsheet) and generates multiple outputs including parameter estimation reports, high-quality plots, and minable XML files. We validated CellPD's estimates by comparing it with a previously published tool (cellGrowth) and with Microsoft Excel's built-in functions. CellPD correctly estimates the net growth rate of cell cultures and is more robust to data sparsity than cellGrowth. When we tested CellPD's usability, biologists (without training in computational modeling) ran CellPD correctly on sample data within 30 min. To demonstrate CellPD's ability to aid in the analysis of high throughput data, we created a synthetic high content screening (HCS) data set, where a simulated cell line is exposed to two hypothetical drug compounds at several doses. CellPD correctly estimates the drug-dependent birth, death, and net growth rates. Furthermore, CellPD's estimates quantify and distinguish between the cytostatic and cytotoxic effects of both drugs-analyses that cannot readily be performed with spreadsheet software such as Microsoft Excel or without specialized computational expertise and programming environments. CONCLUSIONS: CellPD is an open source tool that can be used by scientists (with or without a background in computational or mathematical modeling) to quantify key aspects of cell phenotypes (such as cell cycle and death parameters). Early applications of CellPD may include drug effect quantification, functional analysis of gene knockout experiments, data quality control, minable big data generation, and integration of biological data with computational models.

Immune responses to a class II helper peptide epitope in patients with stage III/IV resected melanoma.

The importance of CD8(+) cytolytic T cells for protection from viral infection and in the generation of immune responses against tumors has been well established. In contrast, the role of CD4(+) T-helper cells in human infection and in cancer immunity has yet to be clearly defined. In this pilot study, we show that immunization of three resected, high-risk metastatic melanoma patients with a T-helper epitope derived from the melanoma differentiation antigen, melanoma antigen recognized by T cells-1, results in CD4(+) T-cell immune responses. Immune reactivity to that epitope was detected by DR4-peptide tetramer staining, and enzyme-linked immunospot assay of fresh and restimulated CD4(+) T cells from patients over the course of the 12-month vaccine regimen. The postvaccine CD4(+) T cells exhibited a mixed T-helper 1/T-helper 2 phenotype, proliferated in response to the antigen and promiscuously recognized the peptide epitope bound to different human leukocyte antigen-DRbeta alleles. For 1 DRbeta1*0401(+) patient, antigen-specific CD4(+) T cells recognized human leukocyte antigen-matched antigen-expressing tumor cells, secreted granzyme B, and also exhibited cytolysis that was MHC class II-restricted. These data establish the immunogenicity of a class II epitope derived from a melanoma-associated antigen and support the inclusion of class II peptides in future melanoma vaccine therapies.

A phase I trial of SD-9427 (progenipoietin) with a multipeptide vaccine for resected metastatic melanoma.

PURPOSE: The melanoma tumor antigen epitope peptides MART-1(26-35 (27L)), gp100(209-217 (210M)),and tyrosinase(368-376 (370D)) were emulsified with incomplete Freund's adjuvant and administered with SD-9427 (progenipoietin), an agonist of granulocyte colony-stimulating factor and the FLT-3 receptor, to evaluate the toxicities of and immune responses to this regimen as primary end points and time to relapse and survival as secondary end points. EXPERIMENTAL DESIGN: Fifteen patients with high-risk resected stage III and IV melanoma were enrolled. Each patient received peptides + incomplete Freund's adjuvant with SD-9427 at doses of either 10, 20, or 40 microg/kg s.c. for 3 days before and 7 days after each vaccination. Immunizations were administered every month for 6 months and then administered once 6 months later. A leukapheresis to obtain peripheral blood mononuclear cells for immune analyses as well as skin testing with peptides and recall antigens was performed before and after vaccination. IFN- gamma release assay, ELISPOT, and MHC-peptide tetramer analysis were performed using peripheral blood mononuclear cells collected before and after vaccination to evaluate peptide-specific cytotoxic T-cell responses. RESULTS: Local pain and granuloma formation and fatigue of grade I or II were the most common side effects. One patient developed antibody-mediated leukopenia and transient grade III neutropenia that resolved after stopping SD-9427. Six of 12 patients tested developed a positive skin test response to one or more of the peptides. Seven of 10 patients tested demonstrated an immune response to at least one peptide when evaluated by IFN-gamma release assay and ELISPOT assay after vaccination, as did 11 of 12 patients analyzed by MHC-peptide tetramer assay. Four of 15 patients have relapsed with a median follow-up of 20 months, and 1 patient in this high-risk group has died of disease. CONCLUSIONS: SD-9427 with a multipeptide vaccine was generally well tolerated, although one patient developed reversible antibody-mediated neutropenia. These data suggest that the majority of patients with resected melanoma mount an antigen-specific immune response against a multipeptide vaccine administered with SD-9427.

Making dendritic cells from the inside out: lentiviral vector-mediated gene delivery of granulocyte-macrophage colony-stimulating factor and interleukin 4 into CD14+ monocytes generates dendritic cells in vitro.

We have evaluated a one-hit lentiviral transduction approach to genetically modifying monocytes in order to promote autocrine and paracrine production of factors required for their differentiation into immature dendritic cells (DCs). High-titer third-generation self-inactivating lentiviral vectors expressing granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4) efficiently achieved simultaneous and persistent codelivery of the transgenes into purified human CD14+ monocytes. Coexpression of GM-CSF and IL-4 in CD14+ cells was sufficient to induce their differentiation into a DC-like phenotype, as evidenced by their morphology, immature immunophenotypic profile (CD14-, CD1a+, CD80+, CD86+, MHC-I+, MHC-II+), and their ability to further develop into a mature phenotype (CD83+) on further treatment with soluble CD40 ligand. Mixed lymphocyte reactions showed that the T cell-stimulating activity of lentivirus-modified DCs was superior to that of DCs grown by conventional methods. Lentivirus-modified DCs displayed efficient antigen-specific, MHC class I-restricted stimulation of autologous CD8+ T cells, as shown by IFN-gamma production and CTL assays. DCs coexpressing GM-CSF and IL-4 could be kept metabolically active and viable in culture for 14 days in the absence of exogenously added growth factors, unlike conventionally produced DCs. Coexpression of FLT3 ligand did not improve the viability, expansion, or immunologic performance of lentivirus-modified DCs. This article demonstrates the proof-of-concept to genetically convert monocytes to DC-type antigen-presenting cells with lentiviral vectors.

Large-scale monocyte enrichment coupled with a closed culture system for the generation of human dendritic cells.

Conventional methods for generating monocyte-derived dendritic cells (DC) for clinical trials utilize the property of plastic adherence to select monocytes from leukapheresis samples. This method is labor-intensive and has the potential for contamination at various steps. We evaluated a large-scale monocyte enrichment procedure using a cell selector (Isolex 300i(R)) followed by culture in a sterile bag system (Stericell(R)) for generation of DC. DC generated in tissue culture flasks after monocyte selection by plastic adherence were compared to those generated in Stericell(R) bags after monocyte enrichment by negative selection with the Isolex(R) 300i. DC were matured with lipopolysaccharide and pulsed with a peptide derived from the melanoma antigen gp100. Peptide-pulsed DC cultured by the two techniques were evaluated for phenotype, viability, ability to induce allogeneic and peptide-specific autologous proliferative responses as well as peptide-specific cytotoxic T-cell responses. The mean monocyte yield from leukapheresis collections was 17+/-2.4%, which increased to 52+/-11% after Isolex(R) selection. The DC yield of plated mononuclear cells from flasks or bags was 2.7+/-0.96% and 4.84+/-2.65%, respectively. DC cultured by both methods expressed high levels of CD86, CD80, CD40, CD83, CD44, CD11c and CD58, and was comparable in their ability to induce allogeneic and peptide-specific autologous proliferative responses as well as gp100 peptide-specific cytotoxic T-cell responses. These results indicate that potent monocyte-derived DC can be generated in a closed culture bag system after monocyte enrichment by immunomagnetic negative selection. Due to the closed nature of the enrichment and culture systems, the potential for contamination is minimized. This protocol is well suited for culturing large numbers of DC for clinical immunotherapy trials.