Evaluation of automated Wes system as an analytical and characterization tool to support monoclonal antibody drug product development

Recommendations for Development and Validation of a Fit-For-Purpose Biomarker Assays Using Western Blotting; An-AAPS Sponsored Initiative to Harmonize Industry Practices

Western blot (WB) assays are routinely used for detection and quantification of biomarkers. Although assay validation to measure biomarkers in complex matrices has become a mainstay process for ligand binding assays (LBA) and mass spectrometry (MS), no guidelines exist yet validate biomarker methods using WB techniques. In this cross-industry white paper, we outlined in detail the key steps for development and for validation of WB assays for protein biomarkers under different contexts of use (COU). In addition, we described how to determine the level of assay validation needed for biomarker assays using Western blotting. For simplicity, we described two paths of WB assay validation. The first path (Path 1) is for biomarkers being analyzed for exploratory research or for internal go- or no/go- decision making. The second path (Path 2) is for clinical decision making such as dose determination or drug response that need to be run in a regulated environment. This work is supported through AAPS Biomarkers and Precision Medicine subteam and represents AAPS members opinion.

Beneficial effect of heat-killed Lactiplantibacillus plantarum L-137 on intestinal barrier function of rat small intestinal epithelial cells

Heat-killed Lactiplantibacillus plantarum L-137 (HK L-137) has been suggested to enhance the intestinal barrier in obese mice, leading to improvement of metabolic abnormalities and adipose tissue inflammation, and in healthy humans with overweight, leading to improvement of systemic inflammation. However, its detailed mechanism of action has not been clarified. Therefore, this study investigated the effects of HK L-137 on the permeability of rat small intestinal epithelial IEC-6 cells, tight junction-related gene and protein expression and localization, and intracellular signaling pathways involved in barrier function. Treatment of IEC-6 cells with HK L-137 for 26 h significantly reduced the permeability to fluorescein isothiocyanate-dextran (FD-4). HK L-137 also increased gene and protein expression of zonula occludens-1 (ZO-1), an important tight junction protein, without affecting the localization. Furthermore, inhibition of the extracellular signal-regulated kinase (ERK)1/2 pathway in IEC-6 cells canceled the HK L-137-related reduction in permeability to FD-4. Phosphorylation of ERK in IEC-6 cells was induced 15 min after the addition of HK L-137. These results suggest that HK L-137 reduces intestinal permeability partly through activating the ERK pathway and increasing expression of the ZO-1 gene and protein. Enhancement of intestinal barrier function with HK L-137 might be effective in preventing and treating leaky gut, for which no specific therapeutic tool has been established.

Automated Capillary Electrophoresis Immunoblot for the Detection of Alpha-Synuclein in Mouse Tissue

Background

Alpha-synuclein (aSyn) is a key player in neurodegenerative diseases such as Parkinson's disease (PD), dementia with Lewy bodies, or multiple system atrophy. aSyn is expressed throughout the brain, and can also be detected in various peripheral tissues. In fact, initial symptoms of PD are non-motoric and include autonomic dysfunction, suggesting that the periphery might play an important role in early development of the disease. aSyn is expressed at relatively low levels in non-central tissues, which brings challenges for its detection and quantification in different tissues.

Objective

Our goal was to assess the sensitivity of aSyn detection in central and peripheral mouse tissues through capillary electrophoresis (CE) immunoblot, considering the traditional SDS-PAGE immunoblot as the current standard.

Methods

Tissues from central and non-central origin from wild type mice were extracted, and included midbrain, inner ear, and esophagus/stomach. aSyn detection was assessed through immunoblotting using Simple Western size-based CE and SDS-PAGE.

Results

CE immunoblots show a consistent detection of aSyn in central and peripheral tissues. Through SDS-PAGE, immunoblots revealed a reliable signal corresponding to aSyn, particularly following membrane fixation.

Conclusion

Our results suggest a reliable detection of aSyn in central and peripheral tissues using the CE Simple Western immunoblot system. These observations can serve as preliminary datasets when aiming to formally compare CE with SDS-PAGE, as well as for further characterization of aSyn using this technique.

Creating Polyploid Escherichia Coli and Its Application in Efficient L-Threonine Production

Prokaryotic genomes are generally organized in haploid. In synthetic biological research, efficient chassis cells must be constructed to produce bio-based products. Here, the essential division of the ftsZ gene to create functional polyploid E. coli is regulated. The artificial polyploid E. coli containing 2-4 chromosomes is confirmed through PCR amplification, terminator localization, and flow cytometry. The polyploid E. coli exhibits a larger cell size, and its low pH tolerance and acetate resistance are stronger than those of haploid E. coli. Transcriptome analysis shows that the genes of the cell's main functional pathways are significantly upregulated in the polyploid E. coli. These advantages of the polyploid E. coli results in the highest reported L-threonine yield (160.3 g L-1 ) in fed-batch fermentation to date. In summary, an easy and convenient method for constructing polyploid E. coli and demonstrated its application in L-threonine production is developed. This work provides a new approach for creating an excellent host strain for biochemical production and studying the evolution of prokaryotes and their chromosome functions.

MoLrp1-mediated signaling induces nuclear accumulation of MoMsn2 to facilitate fatty acid oxidation for infectious growth of the rice blast fungus

Fatty acid β-oxidation is critical for fatty acid degradation and cellular development. In the rice blast fungus Magnaporthe oryzae, fatty acid β-oxidation is reported to be important mainly for turgor generation in the appressorium. However, the role of fatty acid β-oxidation during invasive hyphal growth is rarely documented. We demonstrated that blocking peroxisomal fatty acid β-oxidation impaired lipid droplet (LD) degradation and infectious growth of M. oryzae. We found that the key regulator of pathogenesis, MoMsn2, which we identified previously, is involved in fatty acid β-oxidation by targeting MoDCI1 (encoding dienoyl-coenzyme A [CoA] isomerase), which is also important for LD degradation and infectious growth. Cytological observations revealed that MoMsn2 accumulated from the cytosol to the nucleus during early infection or upon treatment with oleate. We determined that the low-density lipoprotein receptor-related protein MoLrp1, which is also involved in fatty acid β-oxidation and infectious growth, plays a critical role in the accumulation of MoMsn2 from the cytosol to the nucleus by activating the cyclic AMP signaling pathway. Our results provide new insights into the importance of fatty acid oxidation during invasive hyphal growth, which is modulated by MoMsn2 and its related signaling pathways in M. oryzae.

Turmeronols (A and B) from Curcuma longa have anti-inflammatory effects in lipopolysaccharide-stimulated BV-2 microglial cells by reducing NF-κB signaling

Turmeronols (A and B), bisabolane-type sesquiterpenoids found in turmeric, reduce inflammation outside the brain in animals; however, their effects on neuroinflammation, a common pathology of various neurodegenerative diseases, are not understood. Inflammatory mediators produced by microglial cells play a key role in neuroinflammation, so this study evaluated the anti-inflammatory effects of turmeronols in BV-2 microglial cells stimulated with lipopolysaccharide (LPS). Pretreatment with turmeronol A or B significantly inhibited LPS-induced nitric oxide (NO) production; mRNA expression of inducible NO synthase; production of interleukin (IL)-1β, IL-6, and tumor necrosis factor α and upregulation of their mRNA expression; phosphorylation of nuclear factor-κB (NF-κB) p65 proteins and inhibitor of NF-κB kinase (IKK); and nuclear translocation of NF-κB. These results suggest that these turmeronols may prevent the production of inflammatory mediators by inhibiting the IKK/NF-κB signaling pathway in activated microglial cells and can potentially treat neuroinflammation associated with microglial activation.

Analytical technology development to monitor the stability of Polysaccharide-Protein conjugate vaccines

The covalent attachment of a bacterial-derived capsular polysaccharide to protein is of critical importance in transforming the polysaccharide from an antigen with limited immunogenicity in infants and older adults to an antigen that can prevent potentially fatal disease. For a polysaccharide-protein conjugate vaccine (PCV) candidate to be successful, it must be sufficiently stable. Chemical breakage of carbohydrate bonds in the polysaccharide may result in the reduction of "conjugate dose" and could negatively impact immunogenicity and the ability of the vaccine to prime for memory responses. Therefore, development of analytical tools to monitor the integrity of a polysaccharide-protein conjugate (glycoconjugate) vaccine is of practical significance. In this work, reducing SDS-PAGE, Intrinsic Protein Fluorescence Spectroscopy (IPFS), Differential Scanning Fluorimetry (DSF) were evaluated methods to study the impact of time, temperature, and formulation composition on the stability of a glycoconjugate vaccine prepared by multisite coupling of polysaccharide to a carrier protein. In addition, an automated capillary Western system was also evaluated to study the impact of storage on glycoconjugate vaccine stability. Two streptococcus pneumoniae polysaccharide-protein conjugates (serotype 3 and serotype 19A) were chosen to examine their physicochemical stability when formulated as a single antigen vaccine. While all methods require only a small amount of test article and can test multiple samples per assay run, automated capillary Western has the additional advantage of being highly sensitive even at low concentrations in complex vaccine formulations that contain aluminum adjuvant and multiple antigens. Results suggest that automated capillary Western is stability-indicating and may be an effective analytical technology tool for the formulation development of a multivalent glycoconjugate vaccine.

Capillary Western Immunoassay Optimization of Estrogen Related Factors in Human Subcutaneous Adipose Tissue

Lipedema is a multifaceted chronic fat disorder characterized by the bilateral and disproportionate accumulation of fat predominantly in the lower body regions of females. Research strongly supports that estrogen factors likely contribute to the pathophysiology of this disease. We aim to help demonstrate this link by quantifying estrogen factor differences between women with and without lipedema. For time and lipedema adipose tissue conservation, the Protein Simple WES machine will be utilized in place of traditional western blotting. Here, we are interested in evaluating estrogen related factors, such as, but not limited to, estrogen receptors and enzymes involved in the successive conversions of cholesterol and androgens to estrogens in human subcutaneous adipose. Evaluation of these factors within adipose tissue, however, is novel for this instrument. Thus, we optimized tissue lysis and protein extraction for 11 proteins of interest. Antibodies and their working concentrations were determined based upon specific and distinguishable (signal-to-noise) peaks from electropherogram outputs across different tissue lysate concentrations. We found that overnight acetone precipitation proved to be the best procedure for extracting protein from lipid rich adipose tissue samples. Six of the eleven proteins were found to migrate to their expected molecular weights, however, five did not. For proteins that did not migrate as expected, overexpression lysates and empty vector controls were used to validate detection antibodies. Protein extract from subcutaneous adipose tissue and overexpression lysates were then combined to understand if migration was specifically altered by adipose tissue. From these results, we concluded that the lipid rich nature of adipose tissue in combination with the separation matrix designated for use with the WES were preventing the appropriate migration of some proteins rather than non-specific antibody binding or inappropriate preparation methods.

Genomic profile of radiation-induced early-onset mouse B-cell lymphoma recapitulates features of Philadelphia chromosome-like acute lymphoblastic leukemia in humans

Epidemiological studies have revealed a radiation-related increase in the risk of developing acute lymphoblastic leukemia (ALL). Our recent study revealed early induction and increased risk of precursor B-cell (pB) lymphomas in mice after radiation exposure. However, the genomic landscape of radiation-induced B-cell lymphomas remains unclear. To identify the relevant genetic alterations in mice, whole-exome sequencing was performed on both early-onset and late-onset B-cell lymphomas that developed spontaneously or after gamma-irradiation. In addition to multiple driver mutations, the data revealed that interstitial deletion of chromosome 4, including Pax5, and missense mutations in Jak3 are unique genomic alterations in radiation-induced, early-onset B-cell lymphomas. RNA sequencing revealed a pB-cell-type gene-expression profile with no involvement of known fusion genes for human ALLs in the early-onset B-cell lymphomas. Activation of Jak3/Stat5 signaling in early-onset B-cell lymphomas was validated using western capillary electrophoresis. Those features were similar to those of Philadelphia chromosome-like ALL. Our data suggest a critical role for Pax5 loss-of-function mutations in initiating B-cell leukemogenesis coupled with activation of Jak3/Stat5 signaling as a basis for the rapid development of radiation-induced pB-ALL. These molecular signatures for radiation-induced cancers will inform both risk assessment and potential targeted therapies for pB-ALL.

Quantitative microcapillary electrophoresis immunoassay (mCE IA) for end-to-end analysis of pertactin within in-process samples and Quadracel® vaccine

Protein concentration is an important attribute in the production of subunit or component-based vaccine antigens. Rigorous monitoring of protein concentration is required to identify potential areas for yield improvement. The current GMP method for quantitation is the plate-based ELISA which requires numerous hands-on steps and has low sensitivity in comparison to new microfluidic systems. To address this issue, a sensitive automated microCapillary Electrophoresis ImmunoAssay (mCE IA) method was developed to accurately separate and quantitate pertactin (PRN), an important antigen of the modern acellular Pertussis (aP) vaccine. PRN is reported to be a low-yielding antigen; thus, it is critical to observe its concentration throughout its manufacturing process. First, a primary antibody for PRN was identified to establish suitable immunoprobing conditions for detection of PRN over a wide linear dynamic range that spans 3 orders of magnitude. Next, the pre-adsorbed PRN Drug Substance (DS) was used as a reference standard to quantitate PRN samples against a calibration curve with adequate accuracy and precision. Four representative samples including three in-process steps and final adjuvanted drug product: Quadracel®, were examined to demonstrate the capability of mCE IA to quantitate PRN with high sensitivity and specificity. The matrices of the selected samples contain additional components (e.g. other proteins, growth factors, cell culture media, residual ammonium sulfate, and aluminum adjuvant) often making the quantitation of PRN challenging. The specificity and method linearity were demonstrated by spiking pre-adsorbed PRN DS into the four representative samples. In addition, it was shown that reportable concentrations of PRN for nine downstream process steps as analyzed by our method is comparable to concentrations obtained with ELISA. Most importantly, this study demonstrated that our method's quantitative accuracy is independent of matrix components, as each sample undergoes extensive dilution. This allows for seamless end-to-end analysis of PRN from fermenter harvest, through to complex downstream process samples to adjuvanted drug products. Finally, for the first time the developed and qualified mCE IA method was shown to quantify PRN throughout the entire manufacturing process to provide rapid feedback for process optimizations allowing for accurate yield and step-loss calculations.

Combining radiation to EGFR and Bcl-2 blockade: a new approach to target cancer stem cells in head and neck squamous cell carcinoma

PURPOSE

The clinical outcome of head and neck squamous cell carcinoma (HNSCC) remains poor, partly due to the presence of resistant cancer stem cells (CSCs) which are responsible of recurrences. CSCs have low EGFR expression and, conversely, overexpress the anti-apoptotic Bcl-2 protein, which is involved in resistance to apoptosis and the invasion/migration capacities of tumour cells.

METHODS

The combination therapy of ABT-199, a Bcl-2 inhibitor, cetuximab an EGFR inhibitor, and radiation using an HNSCC model (SQ20B cell line) and its corresponding CSC subpopulation were evaluated in vitro (2D/3D cell proliferation; invasion/migration and apoptosis using videomicroscopy) and in vivo.

RESULTS

Cetuximab strongly inhibited 2D and 3D cell proliferation, as well as invasion/migration, only in non-CSC-SQ20B cells, whereas ABT-199 selectively inhibited these mechanisms in SQ20B/CSCs. The combination of irradiation + cetuximab + ABT-199 increased the inhibition of the 2D and 3D cell proliferation, invasion/migration, and resistance to apoptosis in both cell sub-populations. In addition, in a nude mouse model with heterotopic tumour xenograft, a treatment combining cetuximab + ABT-199 with fractional irradiation strongly delayed the tumour growth and increased in vivo lifespan without side effects.

CONCLUSION

Based on the present results, this triple combination therapy may represent a new opportunity for testing in clinical trials, particularly in locally advanced HNSCC.

Development of a novel capillary electrophoresis-based approach for detection of anti-drug antibody responses

Peggy Sue is a capillary-based western/immunoassay platform that can separate and characterize proteins by size or charge. A quick and automated immunogenicity assay was developed on Peggy Sue based on charge separation and compared with a traditional bridging method using preclinical samples from non-human primate studies. The results generated with the Peggy Sue assay were comparable to those of the bridging assays. The Peggy Sue platform has several advantages, including time efficiency, low sample consumption, and easy automation. The platform is especially ideal for further characterization of anti-drug antibody (ADA) specificity against complex biologics such as bispecific or multi-specific biotherapeutics as it is easy to conduct domain specificity assessment of observed ADA responses. Our evaluation suggests that the Peggy Sue platform is a promising tool for preclinical ADA analysis.

A dataset describing a suite of novel antibody reagents for the RAS signaling network

RAS genes are frequently mutated in cancer and have for decades eluded effective therapeutic attack. The National Cancer Institute's RAS Initiative has a focus on understanding pathways and discovering therapies for RAS-driven cancers. Part of these efforts is the generation of novel reagents to enable the quantification of RAS network proteins. Here we present a dataset describing the development, validation (following consensus principles developed by the broader research community), and distribution of 104 monoclonal antibodies (mAbs) enabling detection of 27 phosphopeptides and 69 unmodified peptides from 20 proteins in the RAS network. The dataset characterizes the utility of the antibodies in a variety of applications, including Western blotting, immunoprecipitation, protein array, immunohistochemistry, and targeted mass spectrometry. All antibodies and characterization data are publicly available through the CPTAC Antibody Portal, Panorama Public Repository, and/or PRIDE databases. These reagents will aid researchers in discerning pathways and measuring expression changes in the RAS signaling network.

Characterization of therapeutic antibody fragmentation using automated capillary western blotting as an orthogonal analytical technique

Fragmentation in protein-based molecules continues to be a challenge during manufacturing and storage, and requires an appropriate control strategy to ensure purity and integrity of the drug product. Electrophoretic and chromatographic methods are commonly used for monitoring the fragments. However, size-exclusion chromatography often suffers from low resolution of low molecular weight fragments. Electrophoretic methods like CE-SDS are not compatible with enriching fragments for additional characterization tests such as MS. These limitations may result in inadequate control strategy for monitoring and characterizing fragments for protein-based molecules. Capillary western blotting was used in this study as an orthogonal method for characterization of fragments in an IgG1 antibody under reduced conditions. To achieve a comprehensive mapping of various fragments generated by thermal stress, capillary western profiles were generated using recognition antibodies for IgG kappa (κ) light chain, Fc, and Fab regions that enabled unambiguous fragment identification. Additionally, three different enzymatic digestion methods (IdeS, PNGase F, and IgdE) were applied coupled with capillary western blotting for clip identifications. Finally, complementary data collected using traditional chromatographic and electrophoretic methods allowed to establish a comparison of analytical profiles with an added benefit of fragment identification offered by capillary western profiling. In addition to various Fc and Fab-related low molecular weight fragments, a non-reducible thio-ether linked 75 kDa HL fragment was also identified.

An Automated Immunoblot Method for Detection of IgG Antibodies to Hepatitis C Virus: a Potential Supplemental Antibody Confirmatory Assay

An estimated 41,200 people were newly infected with hepatitis C virus (HCV) in 2016 in the United States. Screening tests for antibodies to HCV may generate up to 32% false positivity in low-risk populations. Current Centers for Disease Control and Prevention (CDC) screening recommendations do not require confirmatory testing of a screening anti-HCV-positive test; however, confirmation is valuable for surveillance in the absence of HCV RNA testing. A recombinant immunoblot assay (RIBA) was used as a confirmatory assay for anti-HCV-reactive samples but was discontinued in 2013. Another anti-HCV confirmatory assay, INNO-LIA, is commercially available in Europe but is not approved by the Food and Drug Administration (FDA) in the United States. We report the development of an anti-HCV assay that was performed on an automated immunoblot platform using a fourth-generation HCV recombinant fusion protein. Based on testing of 70 well-characterized samples, of which 40 were HCV RNA and anti-HCV positive, 15 were HCV RNA positive/anti-HCV negative, and 15 were HCV RNA and anti-HCV negative, the specificity and sensitivity of the HCV-WES assay were 100% and 95%, respectively. Concordance between INNO-LIA and HCV-WES was determined by testing 205 HCV RNA-negative/anti-HCV-positive samples, of which 149 (72.7%) were positive by HCV-WES, while 146 (71.2%) were positive by INNO-LIA. We have shown proof of concept for the use of this test for confirmation of screened anti-HCV results. The HCV-WES assay has advantages over manual Western blot assays and INNO-LIA, including ease of use, lower cost, and reduced hands-on time.

A Multiplexed Mass Spectrometry-Based Assay for Robust Quantification of Phosphosignaling in Response to DNA Damage

A lack of analytically robust and multiplexed assays has hampered studies of the large, branched phosphosignaling network responsive to DNA damage. To address this need, we developed and fully analytically characterized a 62-plex assay quantifying protein expression and post-translational modification (phosphorylation and ubiquitination) after induction of DNA damage. The linear range was over 3 orders of magnitude, the median inter-assay variability was 10% CV and the vast majority (∼85%) of assays were stable after extended storage. The multiplexed assay was applied in proof-of-principle studies to quantify signaling after exposure to genotoxic stress (ionizing radiation and 4-nitroquinoline 1-oxide) in immortalized cell lines and primary human cells. The effects of genomic variants and pharmacologic kinase inhibition (ATM/ATR) were profiled using the assay. This study demonstrates the utility of a quantitative multiplexed assay for studying cellular signaling dynamics, and the potential application to studies on inter-individual variation in the radiation response.

SI-traceable calibration-free analysis for the active concentration of G2-EPSPS protein using surface plasmon resonance

Active proteins play important roles in the function regulation of human bodies and attract much interest for use in pharmaceuticals and clinical diagnostics. However, the lack of primary methods to analyze active proteins means there is currently no metrology standard for active protein measurement. In recent years, calibration-free concentration analysis (CFCA), which is based on surface plasmon resonance (SPR) technology, has been proposed to determine the active concentration of proteins that have specific binding activity with a binding partner without any higher order standards. The CFCA experiment observes the changes of binding rates at totally different two flow rates and uses the known diffusion coefficient of an analyte to calculate the active concentration of proteins, theoretically required, the binding process have to be under diffusion-limited conditions. Measuring the active concentration of G2-EPSPS protein by CFCA was proposed in this study. This method involves optimization of the regeneration buffer and preparation of chip surfaces for appropriate reaction conditions by immobilizing ligands (G2-EPSPS antibodies) on sensor chips (CM5) via amine coupling. The active concentration of G2-EPSPS was then determined by injection of G2-EPSPS protein samples and running buffer over immobilized and reference chip surfaces at two different flow rates (5 and 100μLmin^-1). The active concentration of G2-EPSPS was obtained after analyzing these sensorgrams with the 1:1 model. Using the determined active concentration of G2-EPSPS, the association, dissociation, and equilibrium constants of G2-EPSPS and its antibody were determined to be 2.18 ± 0.03 × 10⁶M^-1s^-1, 5.79 ± 0.06 ×10^-3s^-1, and 2.65 ± 0.06 × 10^-9M, respectively. The performance of the proposed method was evaluated. The within-day precisions were from 3.26% to 4.59%, and the between-day precision was 8.36%. The recovery rate of the method was from 97.46% to 104.34% in the concentration range of 1.5-8nM. The appropriate concentration range of G2-EPSPS in the proposed method was determined to be 1.5-8nM. The active G2-EPSPS protein concentration determined by our method was only 17.82% of that obtained by isotope dilution mass spectrometry, showing the active protein was only a small part of the total G2-EPSPS protein. The measurement principle of the proposed method can be clearly described by equations and the measurement result can be expressed in SI units. Therefore, the proposed method shows promise to become a primary method for active protein concentration measurement, which can benefit the development of certified reference materials for active proteins.

A novel fibroblast growth factor-1 ligand with reduced heparin binding protects the heart against ischemia-reperfusion injury in the presence of heparin co-administration

AIMS

Fibroblast growth factor 1 (FGF1), a heparin/heparan sulfate-binding growth factor, is a potent cardioprotective agent against myocardial infarction (MI). The impact of heparin, the standard of care for MI patients entering the emergency room, on cardioprotective effects of FGF1 is unknown, however.

METHODS AND RESULTS

To address this, a rat model of MI was employed to compare cardioprotective potentials (lower infarct size and improve post-ischemic function) of native FGF1 and an engineered FGF1 (FGF1ΔHBS) with reduced heparin-binding affinity when given at the onset of reperfusion in the absence or presence of heparin. FGF1 and FGF1ΔHBS did not alter heparin's anticoagulant properties. Treatment with heparin alone or native FGF1 significantly reduced infarct size compared to saline (P < 0.05). Surprisingly, treatment with FGF1ΔHBS markedly lowered infarct size compared to FGF1 (P < 0.05). Both native and modified FGF1 restored contractile and relaxation function (P < 0.05 versus saline or heparin). Furthermore, FGF1ΔHBS had greater improvement in cardiac function compared to FGF1 (P < 0.05). Heparin negatively impacted the cardioprotective effects (infarct size, post-ischemic recovery of function) of FGF1 (P < 0.05) but not of FGF1ΔHBS. Heparin also reduced the biodistribution of FGF1, but not FGF1ΔHBS, to the left ventricle. FGF1 and FGF1ΔHBS bound and triggered FGFR1-induced downstream activation of ERK1/2 (P < 0.05); yet, heparin co-treatment decreased FGF1-produced ERK1/2 activation, but not that activated by FGF1ΔHBS.

CONCLUSION

These findings demonstrate that modification of the heparin-binding region of FGF1 significantly improves the cardioprotective efficacy, even in the presence of heparin, identifying a novel FGF ligand available for therapeutic use in ischemic heart disease.