Large-scale heparin-based bind-and-elute chromatography identifies two biologically distinct populations of extracellular vesicles.

Purifying extracellular vesicles (EVs) has been challenging because EVs are heterogeneous in cargo yet share similar sizes and densities. Most surface marker-based affinity separation methods are limited to research or diagnostic scales. We report that heparin chromatography can separate purified EVs into two distinct subpopulations as ascertained by MS/MS: a non-heparin-binding (NHB) fraction that contains classical EV markers such as tetraspanins and a heparin-binding (HB) fraction enriched in fibronectins and histones. Both fractions were similarly fusogenic but induced different transcriptional responses in endothelial cells. While EVs that were purified by conventional, non-affinity methods alone induced ERK1/2 phosphorylation and Ki67, the NHB fraction did not. This result suggests heparin chromatography as an additional novel fractionation step that is inherently scalable, does not lead to loss of material, and separates inflammatory and pyrogenic EVs from unreactive EVs, which will improve clinical applications.

Extracellular Vesicle Isolation by a Tangential-Flow Filtration-Based Large-Scale Purification Method.

Extracellular vesicle (EV) isolation from conditioned cell culture medium has been a challenging topic. It is particularly difficult to obtain pure and intact EVs at a large scale. The commonly used methods such as differential centrifugation, ultracentrifugation, size exclusion chromatography, polyethylene glycol (PEG) precipitation, filtration, and affinity-based purification each have their advantages and limitations. Here, we present a tangential-flow filtration (TFF) based, multi-step purification protocol that combines filtration, PEG precipitation, and Capto Core 700 multimodal chromatography (MMC) to isolate EVs at high purity from large volumes of cell culture conditioned medium. Inserting the TFF step before PEG precipitation removes proteins, which may aggregate in subsequent steps and co-purify with EVs.

Safety and Feasibility of High-Pressure/High-Dose Pressurized Intraperitoneal Aerosol Chemotherapy (HP/HD-PIPAC) for Primary and Metastatic Peritoneal Surface Malignancies.

OBJECTIVE: The aim of this study was to evaluate the feasibility and perioperative safety of high-pressure/high-dose pressurized intraperitoneal aerosol chemotherapy (HP/HD-PIPAC) to manage peritoneal surface malignancies (PSM). METHODS: Retrospective analysis of a prospective database of about 130 consecutive patients scheduled for HP/HD-PIPACs for PSM. Doxorubicin plus cisplatin (PIPAC-C/D) or oxaliplatin (PIPAC-Ox) were nebulized into a constant capnoperitoneum of 20 mmHg at doses of 6, 30, or 120 mg/m2 of body surface area (BSA). Outcome criteria were perioperative complications (Clavien-Dindo). RESULTS: The median age of patients was 62 years (range 9-82), and the primary tumor site was of colorectal (CRC), upper gastrointestinal tract (UGI), unknown primary (CUP), malignant epithelioid mesothelioma of the peritoneum (MPM), hepato-pancreatic-biliary tract (HPB), and other origin in 30 (23.1%), 27 (20.8%), 16 (12.3%), 16 (12.3%), 6 (4.6%), and 35 (26.9%) patients, respectively. Abdominal access failed for a first, second, third, and fourth or more HP/HD-PIPAC in 12/130 (9.2%), 4/64 (6.3%), 6/40 (15.0%), and 2/33 (6.1%) patients. A total of 243 procedures were performed in 118 patients. No intraoperative complications related to increased capnoperitoneal pressure occurred, but an intraoperative bleeding complication was observed in 1/243 (0.4%) patients. The overall rate of postoperative procedure-related complications was 19.3% (47/243), while 15.3% (37/243), 1.6% (6/243), 1.6% (1/243), 0.4% (1/243), and 0.4% (1/243) were Grade I, II, III, IV, and V complications, respectively. CONCLUSIONS: Perioperative complications of HP/HD-PIPAC are comparable with standard pressure/dose PIPAC treatment protocols. Prospective studies are warranted to examine potential improvement in therapy outcomes.

Advances in purification of SARS-CoV-2 spike ectodomain protein using high-throughput screening and non-affinity methods.

The spike (S) glycoprotein of the pandemic virus, SARS-CoV-2, is a critically important target of vaccine design and therapeutic development. A high-yield, scalable, cGMP-compliant downstream process for the stabilized, soluble, native-like S protein ectodomain is necessary to meet the extensive material requirements for ongoing research and development. As of June 2021, S proteins have exclusively been purified using difficult-to-scale, low-yield methodologies such as affinity and size-exclusion chromatography. Herein we present the first known non-affinity purification method for two S constructs, S_dF_2P and HexaPro, expressed in the mammalian cell line, CHO-DG44. A high-throughput resin screen on the Tecan Freedom EVO200 automated bioprocess workstation led to identification of ion exchange resins as viable purification steps. The chromatographic unit operations along with industry-standard methodologies for viral clearances, low pH treatment and 20 nm filtration, were assessed for feasibility. The developed process was applied to purify HexaPro from a CHO-DG44 stable pool harvest and yielded the highest yet reported amount of pure S protein. Our results demonstrate that commercially available chromatography resins are suitable for cGMP manufacturing of SARS-CoV-2 Spike protein constructs. We anticipate our results will provide a blueprint for worldwide biopharmaceutical production laboratories, as well as a starting point for process intensification.

Advances in Purification of SARS-CoV-2 Spike Ectodomain Protein Using High-Throughput Screening and Non-Affinity Methods.

The spike (S) glycoprotein of the pandemic virus, SARS-CoV-2, is a critically important target of vaccine design and therapeutic development. A high-yield, scalable, cGMP-compliant downstream process for the stabilized, soluble, native-like S protein ectodomain is necessary to meet the extensive material requirements for ongoing research and development. As of June 2021, S proteins have exclusively been purified using difficult-to-scale, low-yield methodologies such as affinity and size-exclusion chromatography. Herein we present the first known non-affinity purification method for two S constructs, S_dF_2P and HexaPro, expressed in the mammalian cell line, CHO-DG44. A high-throughput resin screen on the Tecan Freedom EVO200 automated bioprocess workstation led to identification of ion exchange resins as viable purification steps. The chromatographic unit operations along with industry-standard methodologies for viral clearances, low pH treatment and 20 nm filtration, were assessed for feasibility. The developed process was applied to purify HexaPro from a CHO-DG44 stable pool harvest and yielded the highest yet reported amount of pure S protein. Our results demonstrate that commercially available chromatography resins are suitable for cGMP manufacturing of SARS-CoV-2 Spike protein constructs. We anticipate our results will provide a blueprint for worldwide biopharmaceutical production laboratories, as well as a starting point for process intensification.

High throughput chromatography and analytics can inform viral clearance capabilities during downstream process development for biologics.

High throughput process development (HTPD) using liquid handling robotics and RoboColumns is an established methodology in downstream process development to screen chromatography resins and optimize process designs to meet target product profiles. However, HTPD is not yet widely available for use in viral clearance capability of the resin due to a variety of constraints. In the present study, a BSL-1-compatible, non-infectious MVM model, MVM-VLP, was tested for viral clearance assessment with various resin and membrane chromatography operations in a HTPD mode. To detect the MVM-VLP in the high throughput experiments, an electrochemiluminescence immunoassay (ECLIA) assay was developed with up to 5 logs of dynamic range. Storage time suitability of MVM-VLP solutions in various buffer matrices, in the presence or absence of a glycoprotein vaccine candidate, were assessed. Then, MVM-VLP and a test article monoclonal antibody (mAb) were used in a HTPD design that included commercially available ion exchange media chemistries, elucidating a wide variety of viral clearance ability at different operating conditions. The methodologies described herein have the potential to be a part of the process design stage in biologics manufacturing process development, which in turn can reduce risk associated with viral clearance validation studies.

Identification of hinging hyperplane autoregressive exogenous model using efficient mixed-integer programming.

A computationally efficient algorithm for hinging hyperplane autoregressive exogenous (HHARX) model identification via mixed-integer programming technique is proposed in this paper. The HHARX model is attractive since it accurately approximates a general nonlinear process as a sum of hinge functions and preserves the continuity even in a piecewise affine form. Traditional mixed-integer programming-based method for HHARX model identification can only be applied on small-scale input/output datasets due to its significant computational demands. The contribution of this paper is to develop a sequential optimization approach to build accurate HHARX model more efficiently on a relatively large number of experimental data. Moreover, the proposed framework can handle more difficult and practical cases in piecewise model identification, such as: limited submodel switching, missing output data and specified steady state. Finally, the efficiency and accuracy of the proposed computational scheme are demonstrated through modeling of two simulated examples and a pilot-scale heat exchanger.