Low Immunogenic Profile Research Articles

The concept of gene therapy for glaucoma: the dream that has not come true yet.

Gene therapies, despite of being a relatively new therapeutic approach, have a potential to become an important alternative to current treatment strategies in glaucoma. Since glaucoma is not considered a single gene disease, the identified goals of gene therapy would be rather to provide neuroprotection of retinal ganglion cells, especially, in intraocular-pressure-independent manner. The most commonly reported type of vector for gene delivery in glaucoma studies is adeno-associated virus serotype 2 that has a high tropism to retinal ganglion cells, resulting in long-term expression and low immunogenic profile. The gene therapy studies recruit inducible and genetic animal models of optic neuropathy, like DBA/2J mice model of high-tension glaucoma and the optic nerve crush-model. Reported gene therapy-based neuroprotection of retinal ganglion cells is targeting specific genes translating to growth factors (i.e., brain derived neurotrophic factor, and its receptor TrkB), regulation of apoptosis and neurodegeneration (i.e., Bcl-xl, Xiap, FAS system, nicotinamide mononucleotide adenylyl transferase 2, Digit3 and Sarm1), immunomodulation (i.e., Crry, C3 complement), modulation of neuroinflammation (i.e., erythropoietin), reduction of excitotoxicity (i.e., CamKIIα) and transcription regulation (i.e., Max, Nrf2). On the other hand, some of gene therapy studies focus on lowering intraocular pressure, by impacting genes involved in both, decreasing aqueous humor production (i.e., aquaporin 1), and increasing outflow facility (i.e., COX2, prostaglandin F2α receptor, RhoA/RhoA kinase signaling pathway, MMP1, Myocilin). The goal of this review is to summarize the current state-of-art and the direction of development of gene therapy strategies for glaucomatous neuropathy.

The Use of Adeno-associated virus (AAV) in Vaccine Development


 Adeno-associated virus (AAV) is a very tiny (20-26 nm) icosahedral and non-enveloped virus, and it belongs to the Parvoviridae family. AAV vectors are the most widely used option for gene therapy and delivery of therapeutic antibodies due to their relatively low immunogenicity, high safety profile, broad tropism, and their tendency to maintain long-term gene expression [1]. AVV vectors are developed by transfection of human embryonic kidney (HEK) 293 T cells with transgene, packaging and helper plasmids [2]. Several clinical studies have investigated the use of AAV vectors for gene therapy in treating of Parkinson’s disease, Alzheimer’s disease, heart disease, and prostate cancer [3]. AAV vectors have previously been used to treat muscular diseases, but in recent years, their usage as vaccine vectors to cure or prevent infectious diseases including HIV, HPV, and influenza has expanded [4].
 
 Here, we discuss the advantages and disadvantages of the use of AAV in vaccine development, and future approaches in improving the drawbacks caused by AAV-based vaccines. Numerous animal investigations have been conducted to explore vaccine vectors against various illnesses, suggesting a possibility for AAV-based vaccinations. Clinical studies on humans are, however, uncommon because, in contrast to other viral vectors, AAV induces a poor humoral and cellular immune response. Additionally, infectious vaccinations often target a large group of healthy individuals across a variety of ages, including children and teenagers. Therefore, compared to AAV-based gene therapies, vaccinations based on AAV vectors need to be more cost-effective and need more robust safety control.
 
 According to several research, AAV vector vaccines have been shown to induce a stronger or longer lasting antibody response in comparison to other vaccination approaches, such as DNA, recombinant proteins, inactivated viruses, or virus-like particles (VLPs) [5]. However, AAV vectors are thought to have a low immunogenic profile in comparison to other viral vectors. The main limitations of AAV vectors are their low transgenic capacity and widespread pre-existing immunity in humans [6]. Currently, strategies for improving AAV immunogenicity and circumventing pre-existing immunity are actively being investigated. The research undertaken so far have highlighted numerous significant benefits of AAV vectors for immunisation. Despite all the advantages, there are still a variety of challenges that limit the use of these vectors as a vaccine in humans. Thus, it is necessary to overcome these challenges in order to make AAV-based vaccines effective.

First-in-class monoclonal antibody (mAb) PBP1510 targeting pancreatic adenocarcinoma upregulated factor (PAUF) for pancreatic cancer (PC) treatment: Preclinical perspectives.

e16274 Background: PAUF has been shown to induce PC cell proliferation, angiogenesis and evasion of immune surveillance, thereby promoting tumour progression and metastasis. PBP1510, a novel humanized IgG1 mAb developed by Prestige Biopharma Limited, Singapore, binds to and neutralizes PAUF with high specificity and affinity. With no available targeted therapies against PAUF, the first in its class, PBP1510, has been granted Orphan Drug Designation by EMA, US FDA and Korea MFDS. Methods: To assess inhibition of migration and invasion of PC in vitro, PC cell lines (CFPAC-1 and BxPC-3) with high expression levels of PAUF, and primary PC cells extracted from patients were treated with PBP1510 or human IgG (negative control). Suitability of cynomolgus monkey as animal model for pharmacokinetic (PK) and toxicity studies was verified by comparing binding affinities of PBP1510 to human and monkey PAUF. PK characteristics and immunogenicity of PBP1510 (up to 20 mg/kg), were examined in single dose studies in 6 monkeys. A 4-week repeated dose toxicity study was also conducted in 32 monkeys with PBP1510 (up to 40 mg/kg). An in vitro tissue cross-reactivity study was also conducted in a full panel of normal human tissues, to assess potential toxicity in humans. Results: PBP1510 suppressed the proliferation of the PC cell lines compared to negative control. The migration and invasion of PBP1510 treated PC cell lines as well as the primary tumour cells from patients was significantly reduced compared to the respective control groups in vitro. Similarity in binding affinity of PBP1510 to human PAUF and monkey PAUF, and amino acid sequence homology between human and monkey PAUF, suggest that monkey is an appropriate animal species for toxicity and PK studies of PBP1510. In monkey studies, a dose-proportional increase in systemic exposure was observed at low and high doses. PBP1510 at doses up to 40 mg/kg was well tolerated by study animals and no notable local or systemic toxicity was observed. Low immunogenic profile of PBP1510 was indicated by an absence of anti-PBP1510 antibodies till up to 57 days (8 doses and 28-day recovery period). These data are used to simulate human PK profile and to derive the starting dose and maximum escalated dose for the upcoming Phase 1 clinical studies. Cross-reactivity results did not reveal non-specific binding of PBP1510 in the human tissues except in the cytoplasm of acinar and duct epithelium in the salivary gland which is not expected to be of major toxicologic significance. Conclusions: The efficacy and safety data presented here, along with the data from in vivo mouse studies demonstrating superior anti-tumour activity of PBP1510 treatment, support further clinical development of PBP1510 as a novel anti-cancer agent to treat PAUF-positive PC. The pivotal step of advancing PBP1510 into initial human studies is now in progress.

Single-Cell Quantification of Triple-AAV Vector Genomes Coexpressed in Neurons.

Adeno-associated viruses (AAVs) are one of the most widely used types of viral vectors for research and gene therapy. AAV vectors are safe, have a low immunogenic profile, and provide efficient and long-term transgene expression in a variety of tissues and organs targeted by a specific serotype. Despite these unique features, therapeutic applications, as well as basic research studies, of AAVs have been limited by their packaging capacity of less than 5 kb. Multiple strategies have been explored to deliver large genes. One strategy is to split large transgenes into two or three fragments and package them into separate AAV capsids, generating dual or triple AAV vectors. Combining the fragments potentially allows reconstitution of an mRNA transcript containing the complete sequence of transgene in the same cell. The success of AAVs as vectors for the delivery of large or multiple genes depends directly on the efficiency of co-transduction. Here, we describe a method to measure the efficacy of codelivery, quantifying the number of AAV vectors per cell. We detail how to calculate the average number of incoming AAV genomes in neurons, given the distribution of cell fluorescence across in vitro and in vivo experimental models. To validate the method, we simulated a triple AAV strategy using three fluorescent-protein-encoding genes. We provide a general protocol for constructing plasmids and producing and purifying AAV vectors. We also include a protocol for triple AAV vector co-transduction in primary neuronal cultures and mouse brain. The method can be applied to multiple organs and tissues for the treatment of disorders caused by mutations in multiple or large genes. These protocols will be useful for researchers working to develop and improve new gene delivery technologies. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Construction of AAV plasmids and production of AAVs Basic Protocol 2: AAV transduction of primary superior cervical ganglia (SCG) neuronal cultures Basic Protocol 3: Mouse surgery, AAV injection, and tissue collection and processing Basic Protocol 4: Image analysis and AAV genome quantification.

Synergy of human platelet lysate and laminin to enhance the neurotrophic effect of human adipose-derived stem cells

Synergy of human platelet lysate and laminin to enhance the neurotrophic effect of human adipose-derived stem cells

Mesenchymal Stem Cell Therapy for Osteogenesis Imperfecta.

The aim of this study was to provide a brief overview on the background and rationale on treating fetuses and children suffering from osteogenesis imperfecta (OI) with mesenchymal stem cells (MSCs). MSCs ability to migrate, engraft, and differentiate into bone cells and to act via paracrine effects on the recipient's tissues makes these cells promising candidates as a clinical therapy for OI. Animal work and limited clinical studies in humans support the use of MSC in treating OI. Off-the-shelf MSC have a good safety profile and exhibit multilineage differentiation potential and a low immunogenic profile and thereby may enable this potential therapy to become widely available. MSC transplantation before and after birth to treat OI is an experimental therapy that is currently tested in the international multicentre phase I/II clinical trial BOOSTB4 that aims to assess the safety and efficacy of fetal MSC transplantation for the treatment of severe types of OI.

P509 Influence of concomitant immunosuppresives in retention rate in Crohn′s Disease patients under ustekinumab in the SUSTAIN Study

Abstract Background Whether to use biologic treatment for inflammatory bowel disease as monotherapy or in combination with immunosuppressives has been a matter of debate in the last years. We aimed to evaluate if immunosuppressants influenced the retention rate of ustekinumab in Sustain, the largest study evaluating its use in clinical practice, having the longest follow-up period reported to date. Methods Retrospective, multicentre study (>60 sites) including patients with active Crohn′s Disease (CD) [(Harvey-Bradshaw (HBI)>4)] who received ≥1 dose of ustekinumab intravenously before July 2018. Data on concomitant immunomodulatory therapy (if any) with azathioprine, mercaptopurine, methotrexate or others at the start of ustekinumab treatment and during follow-up were documented. Clinical remission was defined as HBI≤4 and response as ≥3 points decrease from baseline. Loss of response (LoR) was defined as reappearance of symptoms that led to intensifying the treatment dose, adding another medication to control CD, switching or surgery in patients with short-term remission. The retention rate in patients on ustekinumab receiving or not immunosuppressive treatment was evaluated by descriptive analysis and Kaplan-Meier survival curves. Predictive factors were assessed by Cox-regression. Data quality was assured by remote monitoring. Results 463 CD patients were included. Prior CD treatments to ustekinumab were collected: the majority of patients received steroids, immunosuppressants and biologics. Figure 1 shows the percentage of patients on treatment with each type of drug and whether or not they continued to receive it when they started ustekinumab, in the case of steroids and immunosuppressants. Reasons for discontinuation of previous immunosuppressive treatments for CD were as follows: failure (37.5%), sustained remission (5.8%), adverse event (47.6%), medical decision (4%), other reasons (5.1%). During ustekinumab treatment, 163 patients (35.2%) received immunosuppressants (listed in figure 2). Sixty-six (14.3%) patients had their immunosuppressant withdrawn during treatment. Retention was observed in 77.9% of patients with concomitant immunosuppressive therapy versus 76.3% of patients without. There weren′t statistically significant differences between the two populations (p=0.712). Figure 3. The patient-year discontinuation rate for patients who didn′t receive concomitant immunosuppressants was 17.5 versus 18.9 in those who received them. Conclusion No effectiveness differences were seen by adding immunosuppressants to ustekinumab, reinforcing the low immunogenic profile of this drug and reducing the risk of additional side effects and toxicity.

Cellular and molecular biology of cancer stem cells in melanoma: Possible therapeutic implications.

Malignant melanoma is a tumor characterized by a very high level of heterogeneity, responsible for its malignant behavior and ability to escape from standard therapies. In this review we highlight the molecular and biological features of the subpopulation of cancer stem cells (CSCs), well known to be characterized by self-renewal properties, deeply involved in triggering the processes of tumor generation, metastasis, progression and drug resistance. From the molecular point of view, melanoma CSCs are identified and characterized by the expression of stemness markers, such as surface markers, ATP-binding cassette (ABC) transporters, embryonic stem cells and intracellular markers. These cells are endowed with different functional features. In particular, they play pivotal roles in the processes of tumor dissemination, epithelial-to-mesenchymal transition (EMT) and angiogenesis, mediated by specific intracellular signaling pathways; moreover, they are characterized by a unique metabolic reprogramming. As reported for other types of tumors, the CSCs subpopulation in melanoma is also characterized by a low immunogenic profile as well as by the ability to escape the immune system, through the expression of a negative modulation of T cell functions and the secretion of immunosuppressive factors. These biological features allow melanoma CSCs to escape standard treatments, thus being deeply involved in tumor relapse. Targeting the CSCs subpopulation is now considered an attractive treatment strategy; in particular, combination treatments, based on both CSCs-targeting and standard drugs, will likely increase the therapeutic options for melanoma patients. The characterization of CSCs in liquid biopsies from single patients will pave the way towards precision medicine.

Combinatorial Use of Chitosan Nanoparticles, Reversine, and Ionising Radiation on Breast Cancer Cells Associated with Mitosis Deregulation.

Breast cancer is the most commonly occurring cancer in women worldwide and the second most common cancer overall. The development of new therapies to treat this devastating malignancy is needed urgently. Nanoparticles are one class of nanomaterial with multiple applications in medicine, ranging from their use as drug delivery systems and the promotion of changes in cell morphology to the control of gene transcription. Nanoparticles made of the natural polymer chitosan are easy to produce, have a very low immunogenic profile, and diffuse easily into cells. One hallmark feature of cancer, including breast tumours, is the genome instability caused by defects in the spindle-assembly checkpoint (SAC), the molecular signalling mechanism that ensures the timely and high-fidelity transmission of the genetic material to an offspring. In recent years, the use of nanoparticles to treat cancer cells has gained momentum. This is in part because nanoparticles made of different materials can sensitise cancer cells to chemotherapy and radiotherapy. These advances prompted us to study the potential sensitising effect of chitosan-based nanoparticles on breast cancer cells treated with reversine, which is a small molecule inhibitor of Mps1 and Aurora B that induces premature exit from mitosis, aneuploidy, and cell death, before and after exposure of the cancer cells to X-ray irradiation. Our measurements of metabolic activity as an indicator of cell viability, DNA damage by alkaline comet assay, and immunofluorescence using anti-P-H3 as a mitotic biomarker indicate that chitosan nanoparticles elicit cellular responses that affect mitosis and cell viability and can sensitise breast cancer cells to X-ray radiation (2Gy). We also show that such a sensitisation effect is not caused by direct damage to the DNA by the nanoparticles. Taken together, our data indicates that chitosan nanoparticles have potential application for the treatment of breast cancer as adjunct to radiotherapy.

Next generation of biologics for the treatment of Crohn's disease: an evidence-based review on ustekinumab.

The limited efficacy of the currently available medical therapies in a proportion of patients with Crohn’s disease has led to the research and development of molecules that can block new inflammatory pathways. Ustekinumab is a fully human IgG1 monoclonal antibody which targets the common p40 subunit of the cytokines interleukin-12 as well as interleukin-23. Consequently, the Th1 and Th17 inflammatory responses are inhibited. Ustekinumab has been recently approved for its use in patients with Crohn’s disease. Its efficacy and safety was initially proved in patients with psoriasis and psoriatic arthritis. More recently, three Phase III trials have confirmed its efficacy in patients with Crohn’s disease refractory to anti-tumor necrosis factor therapy. This biologic agent appears safe, with no increased risk of infectious or malignant complications, and a low immunogenic profile.

Expressing Transgenes That Exceed the Packaging Capacity of Adeno-Associated Virus Capsids.

Recombinant adeno-associated virus vectors (rAAV) are being explored as gene delivery vehicles for the treatment of various inherited and acquired disorders. rAAVs are attractive vectors for several reasons: wild-type AAVs are nonpathogenic, and rAAVs can trigger long-term transgene expression even in the absence of genome integration-at least in postmitotic tissues. Moreover, rAAVs have a low immunogenic profile, and the various AAV serotypes and variants display broad but distinct tropisms. One limitation of rAAVs is that their genome-packaging capacity is only ∼5 kb. For most applications this is not of major concern because the median human protein size is 375 amino acids. Excluding the ITRs, for a protein of typical length, this allows the incorporation of ∼3.5 kb of DNA for the promoter, polyadenylation sequence, and other regulatory elements into a single AAV vector. Nonetheless, for certain diseases the packaging limit of AAV does not allow the delivery of a full-length therapeutic protein by a single AAV vector. Hence, approaches to overcome this limitation have become an important area of research for AAV gene therapy. Among the most promising approaches to overcome the limitation imposed by the packaging capacity of AAV is the use of dual-vector approaches, whereby a transgene is split across two separate AAV vectors. Coinfection of a cell with these two rAAVs will then-through a variety of mechanisms-result in the transcription of an assembled mRNA that could not be encoded by a single AAV vector because of the DNA packaging limits of AAV. The main purpose of this review is to assess the current literature with respect to dual-AAV-vector design, to highlight the effectiveness of the different methodologies and to briefly discuss future areas of research to improve the efficiency of dual-AAV-vector transduction.

Improved design of PPRHs for gene silencing.

Nowadays, the modulation of gene expression by nucleic acids has become a routine tool in biomedical research for target validation and it is also used to develop new therapeutic approaches. Recently, we developed the so-called polypurine reverse Hoogsteen hairpins (PPRHs) that show high stability and a low immunogenic profile and we demonstrated their efficacy both in vitro and in vivo. In this work, we explored different characteristics of PPRHs to improve their usage as a tool for gene silencing. We studied the role of PPRH length in the range from 20 to 30 nucleotides. We also proved their higher affinity of binding and efficacy on cell viability compared to nonmodified TFOs. To overcome possible off-target effects, we tested wild-type PPRHs, which proved to be capable of binding to their target sequence with more affinity, displaying a higher stability of binding and a higher effect in terms of cell viability. Moreover, we developed a brand new molecule called Wedge-PPRH with the ability to lock the ds-DNA into the displaced structure and proved its efficacy in prostate and breast cancer cell lines.

Cancer stem cells: perspectives for therapeutic targeting.

Cells with "stemness" and tumor-initiating properties have been isolated from both hematological and solid tumors. These cells denominated as cancer stem cells (CSCs), representing rare populations within tumors, have the ability to metastasize and are resistant to standard therapies and immunotherapy. Heterogeneity and plasticity in the phenotype of CSCs have been described in relation to their tissue origin. Few definitive markers have been isolated for CSCs from human solid tumors, limiting their usage for in vivo identification of these cells. Nevertheless, progress in the emerging CSCs concept has been achieved gaining, at least for some type of tumors, their biological and immunological characterization. The recent identification of molecules and signaling pathways that are up-regulated or aberrantly induced in CSCs allowed the development of small agents for specifically targeting of CSCs. A general low immunogenic profile has been reported for CSCs with, in some cases, the identification of the mechanisms responsible of the impairment of cell-mediated immune responses. These concepts are discussed in the context of this review. Although CSCs still need to be fully characterized, potential candidate markers and/or signaling pathways, to be exploited for the design of novel CSC-targeting therapeutic strategies, are described in this review.

Pharmacological Adjuvant Therapies in Primary Coronary Interventions: Bivalirudin

The direct thrombin inhibitor bivalirudin has gained popularity in cardiovascular medicine over the past decade because, in comparison with unfractionated heparin, it guarantees a predictable dose-related degree of anticoagulation with a low immunogenic profile and, possibly, with reduced rates of major bleeding complications. In the past bivalirudin has been frequently employed in the management of patients with heparin-induced thrombocytopenia. The REPLACE-2, ACUITY and ISAR-REACT4 studies demonstrated bivalirudin non-inferiority in comparison with unfractionated heparin in terms of ischemic end-points with a reduction of the bleeding rate also in patients acute coronary syndrome without ST elevation. Finally the results of the HORIZONS-AMI study positioned this drug as a first choice anticoagulant during percutaneous coronary interventions in patients with ST-elevation myocardial infarction. In fact the bivalirudin alone regimen, compared to unfractionated heparin plus GP2b3a inhibitors, decreased in-hospital bleeding rates and short and long term mortality. Given the body of clinical evidence, bivalirudin is likely to contend to GP2b3a inhibitors the leading place among the proposed anticoagulation strategies in the setting of acute coronary syndromes. The duration of the bivalirudin infusion after PCI and the optimal oral antiplatelet regimen associated to bivalirudin are important issues to be solved in future randomized controlled studies.

Allogeneic Cardiospheres Safely Boost Cardiac Function and Attenuate Adverse Remodeling After Myocardial Infarction in Immunologically Mismatched Rat Strains

We sought to characterize the immunologic profile of allogeneic cardiospheres, which are 3-dimensional, self-assembling, cardiac-derived microtissues, and to evaluate their safety and efficacy in repairing ischemic heart tissue. Intramyocardial injection of autologous cardiospheres ameliorates remodeling and improves global function in infarcted myocardium. It is as yet unknown whether allogeneic cardiospheres are similarly effective without eliciting deleterious immune reactions. We expanded cardiospheres from male Wistar Kyoto rat hearts and injected them surgically in the peri-infarct zone of Wistar Kyoto (syngeneic group, n = 28) and Brown Norway female rats (allogeneic group, n = 29). Female rats from both strains (n = 37) injected with normal saline served as controls. In vitro, cardiospheres expressed a low immunogenic profile and inhibited proliferation of alloreactive T cells. In vivo, cell engraftment was similar in the syngeneic and allogeneic groups 1 week and 3 weeks after transplantation. Reductions in scar size and scar collagen content and increases in viable mass in the risk region were accompanied by improvements in left ventricular function and attenuation of left ventricle remodeling that were sustained during 6 months of follow up. Transplantation of allogeneic cardiospheres increased tissue expression of the regenerative growth factors vascular endothelial growth factor, hepatocyte growth factor, and insulin-like growth factor-1, stimulating angiogenesis. Syngeneic and allogeneic cardiospheres attenuated the inflammatory response observed histologically in the peri-infarct region. Allogeneic cardiospheres increase viable myocardium, decrease scar, improve function, and attenuate adverse remodeling in the infarcted rat heart, without deleterious immunological sequelae. These observations lay the groundwork for developing cardiospheres as a novel off-the-shelf microtissue product for myocardial regeneration.

Establishment and Characterization of Immortalized Human Amniotic Epithelial Cells

Human amniotic epithelial cells (HAEs) have a low immunogenic profile and possess potent immunosuppressive properties. HAEs also have several characteristics similar to stem cells, and they are discarded after parturition. Thus, they could potentially be used in cell therapy with fewer ethical problems. HAEs have a short life, so our aim is to establish and characterize immortalized human amniotic epithelial cells (iHAEs). HAEs were introduced with viral oncogenes E6/E7 and with human telomerase reverse transcriptase (hTERT) to create iHAEs. These iHAEs have proliferated around 200 population doublings (PDs) for at least 12 months. High expression of stem cell markers (Oct 3/4, Nanog, Sox2, Klf4) and epithelial markers (CK5, CK18) were detected by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR). These iHAEs were expanded in ultra-low-attachment dishes to form spheroids similarly to epithelial stem/precursor cells. High expression of mesenchymal (CD44, CD73, CD90, CD105) and somatic (CD24, CD29, CD271, Nestin) stem cell markers was detected by flow cytometry. The iHAEs showed adipogenic, osteogenic, neuronal, and cardiac differentiation abilities. In conclusion, the immortalization of HAEs with the characteristics of stem cells has been established, allowing these iHAEs to become useful for cell therapy and regenerative medicine.

Transplantation of Human Pericyte Progenitor Cells Improves the Repair of Infarcted Heart Through Activation of an Angiogenic Program Involving Micro-RNA-132

Pericytes are key regulators of vascular maturation, but their value for cardiac repair remains unknown. We investigated the therapeutic activity and mechanistic targets of saphenous vein-derived pericyte progenitor cells (SVPs) in a mouse myocardial infarction (MI) model. SVPs have a low immunogenic profile and are resistant to hypoxia/starvation (H/S). Transplantation of SVPs into the peri-infarct zone of immunodeficient CD1/Foxn-1(nu/nu) or immunocompetent CD1 mice attenuated left ventricular dilatation and improved ejection fraction compared to vehicle. Moreover, SVPs reduced myocardial scar, cardiomyocyte apoptosis and interstitial fibrosis, improved myocardial blood flow and neovascularization, and attenuated vascular permeability. SVPs secrete vascular endothelial growth factor A, angiopoietin-1, and chemokines and induce an endogenous angiocrine response by the host, through recruitment of vascular endothelial growth factor B expressing monocytes. The association of donor- and recipient-derived stimuli activates the proangiogenic and prosurvival Akt/eNOS/Bcl-2 signaling pathway. Moreover, microRNA-132 (miR-132) was constitutively expressed and secreted by SVPs and remarkably upregulated, together with its transcriptional activator cyclic AMP response element-binding protein, on stimulation by H/S or vascular endothelial growth factor B. We next investigated if SVP-secreted miR-132 acts as a paracrine activator of cardiac healing. In vitro studies showed that SVP conditioned medium stimulates endothelial tube formation and reduces myofibroblast differentiation, through inhibition of Ras-GTPase activating protein and methyl-CpG-binding protein 2, which are validated miR-132 targets. Furthermore, miR-132 inhibition by antimiR-132 decreased SVP capacity to improve contractility, reparative angiogenesis, and interstitial fibrosis in infarcted hearts. SVP transplantation produces long-term improvement of cardiac function through a novel paracrine mechanism involving the secretion of miR-132 and inhibition of its target genes.

Bivalirudin: a review of the pharmacology and clinical application

Among the current agents in the class of direct thrombin inhibitors, bivalirudin (Angiomax®, The Medicines Company, NJ, USA) has seen increased use in cardiovascular medicine over the past decade through its primary indication as an anticoagulant used during percutaneous coronary interventions. Bivalirudin has been further investigated and used as the anticoagulation strategy in the setting of cardiac and endovascular surgical procedures and is frequently utilized in the management of patients with heparin-induced thrombocytopenia. In comparison with heparin, bivalirudin exhibits a low immunogenic profile and provides similar or reduced major bleeding rates as well as a predictable degree of anticoagulation that is dose related. Bivalirudin primarily undergoes dual elimination via proteolytic cleavage and renal elimination, and requires dose adjustment in the setting of severe renal dysfunction. Given the body of supportive data, bivalirudin is likely to continue to figure prominently as a reliable and efficient anticoagulation strategy. Additional agents in the class of direct thrombin inhibitors are under investigation and may find increasing clinical use.

Approaches to Avoid Immune Responses Induced by Repeated Subcutaneous Injections of Allogeneic Umbilical Cord Tissue-Derived Cells

Cellular treatments for repairing diseased tissues represent a promising clinical strategy. Umbilical cord tissue-derived cells (UTC) are a unique source of cells with a low immunogenic profile and potential for tissue repair. By using UTC from miniature swine, we previously demonstrated that despite their low immunogenic phenotype, UTC could induce an immune response under certain inflammatory conditions and after multiple subcutaneous (SC) injections. Given that repeat dosing of cells may be necessary to achieve a lasting therapeutic benefit, in this study, we examined approaches to avoid an immune response to multiple SC injections of UTC. By using in vitro and in vivo measures of sensitization to SC cellular injections, we assessed the effects of varying the location of administration site, prolongation of timing between injections, and use of immunosuppressive treatments on repeated cellular injections in Massachusetts General Hospital major histocompatibility complex-defined miniature swine. Although under normal conditions, a single SC injection of major histocompatibility complex-mismatched UTC did not induce a detectable immune response, multiple SC injections of UTC demonstrated rapid humoral and cell-mediated immune responses. Avoidance of an immune response to repeat SC injection was achieved by concurrent immunosuppression with each dose of UTC. UTC and other similar cell types believed to be nonimmunogenic have the potential to induce immune responses under certain conditions. These studies provide important considerations and guidelines for preclinical studies investigating allogeneic cellular therapies.

Amnion Epithelial Cell Isolation and Characterization for Clinical Use

Human amnion epithelial cells (hAECs) are a heterologous population positive for stem cell markers; they display multilineage differentiation potential, differentiating into cells of the endoderm (liver, lung epithelium), mesoderm (bone, fat), and ectoderm (neural cells). They have a low immunogenic profile and possess potent immunosuppressive properties. Hence, hAECs may be a valuable source of cells for cell therapy. This unit describes an efficient and effective method of hAEC isolation, culture, and cryopreservation that is animal product-free and in accordance with current guidelines on preparation of cells for clinical use. Cells isolated using this method were characterized after 5 passages by analysis of karyotype, cell cycle distribution, and changes in telomere length. The differentiation potential of hAECs isolated using this animal product-free method was demonstrated by differentiation into lineages of the three primary germ layers and expression of lineage-specific markers analyzed by PCR, immunocytochemistry, and histology.