Monkey Model Research Articles

Engineered human spinal cord-like tissues with dorsal and ventral neuronal progenitors for spinal cord injury repair in rats and monkeys.

Transplanting human neural progenitor cells is a promising method of replenishing the lost neurons after spinal cord injury (SCI), but differentiating neural progenitor cells into the diverse types of mature functional spinal cord neurons in vivo is challenging. In this study, engineered human embryonic spinal cord-like tissues with dorsal and ventral neuronal characters (DV-SC) were generated by inducing human neural progenitor cells (hscNPCs) to differentiate into various types of dorsal and ventral neuronal cells on collagen scaffold in vitro. Transplantation of DV-SC into complete SCI models in rats and monkeys showed better therapeutic effects than undifferentiated hscNPCs, including pronounced cell survival and maturation. DV-SC formed a targeted connection with the host's ascending and descending axons, partially restored interrupted neural circuits, and improved motor evoked potentials and the hindlimb function of animals with SCI. This suggests that the transplantation of pre-differentiated hscNPCs with spinal cord dorsal and ventral neuronal characteristics could be a promising strategy for SCI repair.

Enhanced Beta2-band Oscillations Denote Auditory Hallucination in Schizophrenia Patients and a Monkey Model of Psychosis.

An electroencephalographic (EEG) signature of auditory hallucinations (AHs) is important for facilitating the diagnosis and treatment of AHs in schizophrenia. We recorded EEG from 25 schizophrenia patients with recurrent AHs. During the period of AHs, EEG recordings exhibited significantly elevated beta2-band power in the temporal region, as compared to those recorded in the absence of AHs or during stimulation with verbal sounds. We further generated methamphetamine-treated rhesus monkeys exhibiting psychosis-like behaviors, including repetitive sudden searching actions in the absence of external intrusion, suggesting the occurrence of AHs. Epidural EEG beta2-band power in the temporal region of these monkeys was enhanced immediately after methamphetamine treatment and positively correlated with the frequency of sudden searching actions. Thus, the enhancement of temporal beta2-band oscillations represents a signature for AHs in both patients and a monkey model of psychosis, and this monkey model can be used for developing closed-loop neuromodulation approaches for the treatment of refractory AHs in schizophrenia.

Translational physiologically-based pharmacokinetic model for ocular disposition of monoclonal antibodies.

We have previously published a PBPK model comprising the ocular compartment to characterize the disposition of monoclonal antibodies (mAbs) in rabbits. While rabbits are commonly used preclinical species in ocular research, non-human primates (NHPs) have the most phylogenetic resemblance to humans including the presence of macula in the eyes as well as higher sequence homology. However, their use in ocular research is limited due to the strict ethical guidelines. Similarly, in humans the ocular samples cannot be collected except for the tapping of aqueous humor (AH). Therefore, we have translated this rabbit model to monkeys and human species using literature-reported datasets. Parameters describing the tissue volumes, physiological flows, and FcRn-binding were obtained from the literature, or estimated by fitting the model to the data. In the monkey model, the values for the rate of lysosomal degradation for antibodies (Kdeg), intraocular reflection coefficients (σaq, σret, σcho), bidirectional rate of fluid circulation between the vitreous chamber and the aqueous chamber (QVA), and permeability-surface area product of lens (PSlens) were estimated; and were found to be 31.5h-1, 0.7629, 0.6982, 0.9999, 1.64 × 10-5 L/h, and 4.62 × 10-7 L/h, respectively. The monkey model could capture the data in plasma, aqueous humor, vitreous humor and retina reasonably well with the predictions being within twofold of the observed values. For the human model, only the value of Kdeg was estimated to fit the model to the plasma pharmacokinetics (PK) of mAbs and was found to be 24.4h-1 (4.14%). The human model could also capture the ocular PK data reasonably well with the predictions being within two- to threefold of observed values for the plasma, aqueous and vitreous humor. Thus, the proposed framework can be used to characterize and predict the PK of mAbs in the eye of monkey and human species following systemic and intravitreal administration. The model can also facilitate the development of new antibody-based therapeutics for the treatment of ocular diseases as well as predict ocular toxicities of such molecules following systemic administration.

A phased array ultrasound system with a robotic arm for neuromodulation.

Ultrasonic neuromodulation (UNMOD) provides a non-invasive brain stimulation. However, the high-resolution region-specificity of UNMOD with a single element transducer combined with a mechanical positioning system could have limits due to the intrinsic positioning error from mechanical systems. A phased array system could lead to highly selective neuromodulation with electronic control. A specialized phased-array system with a robotic arm is implemented for a rhesus monkey model. Various primary motor cortex areas related to tail, hand, and mouth were stimulated with a 200μm step size. The ultrasonic parameters were ISPTA of 840mW/cm2, pulse repetition frequency of 100Hz, and a 5% duty factor at 600kHz. The induced movement were recorded and analyzed. Separate digits, mouth, and tongue motions were successfully induced by electronically controlling the focus. The identical body part movement could be induced when the focus was moved back to the identical primary motor cortex with electronic control. Accordingly, the reproducibility of UNMOD could be partially validated with rhesus monkey model. A phased-array system appears to have a potential for the non-invasive and region-selective neuromodulation method.

Long-term drinking stability in the open-access self-administration monkey model

The Non-Human Primate (NHP) model for the study of Alcohol Use Disorders (AUD) as developed in our laboratories is critical to our understanding of the pathophysiology of voluntary, chronic, ethanol consumption. Previous work in this model established categories of ethanol consumption that parallel reported categories of human consumption across a spectrum spanning low drinking, binge drinking, heavy drinking, and very heavy drinking, albeit at generally higher daily intakes across categories than documented in people. Original categories assigned to ethanol consumption patterns were established using a limited cohort of rhesus macaques. This study revisits the validity of categorical drinking using an additional 28 monkeys. In addition to finding categorical representations consistent with the original 2014 report, our findings demonstrate that drinking categories remain stable across the observed 12 months of nearly consistent access to ethanol (22 h/day), termed “open access”. Animals occupying the two ends of the spectrum, “low” and “very heavy” drinkers, exhibit the largest stability. The findings also indicate a slight escalatory drift over time, with very heavy drinking animals experiencing fatigue near the end of open access.

Implementation of Visible monkey into general-purpose Monte Carlo codes: MCNP, PHITS, and Geant4

Recently, a new monkey computational phantom, called Visible Monkey, was developed for non-ionizing radiation studies in animal research. In this study, we extended its applications to ionizing radiation studies by implementing the voxel model of the Visible Monkey into three general-purpose Monte Carlo (MC) codes: MCNP6, PHITS, and Geant4. The implementation work for MCNP and PHITS was conducted using the LATTICE, UNIVERSE, and FILL cards. The G4VNestedParameterisation class was used for Geant4. Then, organ dose coefficients (DCs) for idealized photon beams in the antero-posterior direction were calculated using the three codes and compared, showing excellent agreement (differences <3%). Additionally, organ DCs in other directions (postero-anterior, left-lateral, and right-lateral) were calculated and compared with those of the newborn and 1-year-old reference phantoms. Significant differences were observed (e.g., the stomach DC of the monkey was 5-fold greater than that of the 1-year-old phantom at 0.03 MeV) while the differences tended to decrease with increasing energy (mostly <20% at 10 MeV). The results of this study allows conducting MC simulations using the Visible Monkey to estimate organ-level doses, which should be valuable to support/improve monkey experiments involving ionizing radiation exposures.

Immunomodulatory potential of human clonal mesenchymal stem cells and their extracellular vesicle subpopulations in an inflammatory-mediated diabetic Rhesus monkey model

AimsThis study aimed to investigate the therapeutic potential of a homogenous clonal population of mesenchymal stem cells (cMSC) and their extracellular vesicles (cMSC-EV) subpopulations on isolated rat islets in vitro and in inflammatory-mediated type 1 diabetes (T1D) non-human primate models. Main methodsEV subpopulations were isolated from human bone marrow-derived cMSC supernatant by low- and high-speed ultracentrifuge (EV-20K and EV-U110K) and sucrose density gradient (EV-S110K). The EVs were characterized generally and for the level of albumin, acetylcholinesterase (AChE) activity, co-isolate apoptotic markers, and expression of CD63+/annexin V+. Rat islet-derived single cells (iSCs) proliferation was measured using a Ki-67 proliferation assay. Diabetes was induced by multiple low-dose administrations of streptozotocin in rhesus monkeys. The diabetic monkeys were divided into three groups: the cMSC group, received two injections of 1.5 × 106 cMSC/kg body weight; the EV group received two injections of EVs isolated from 1.5 × 106 cMSC/kg, and the vehicle group received phosphate-buffered saline. Key findingsEV-S110K showed higher AChE activity, lower expression of CD63+/annexin V+, and lower apoptotic co-isolates. EV-S110K induced β-cell proliferation in vitro in a dose-dependent manner. The administration of EV-S110K and/or cMSC in diabetic monkeys demonstrated no significant changes in general diabetic indices and β-cell mass in the pancreas of the monkeys. Both treatments demonstrated a lowering trend in blood glucose levels and reduced pro-inflammatory cytokines. In contrast, regulatory T cells and anti-inflammatory cytokines were increased. SignificancecMSC and cMSC-EV provided initial evidence to attenuate clinical symptoms in inflammatory-mediated T1D non-human primates through immunomodulation.

CATI: an efficient gene integration method for rodent and primate embryos by MMEJ suppression

The efficiency of homology-directed repair (HDR) plays a crucial role in the development of animal models and gene therapy. We demonstrate that microhomology-mediated end-joining (MMEJ) constitutes a substantial proportion of DNA repair during CRISPR-mediated gene editing. Using CasRx to downregulate a key MMEJ factor, Polymerase Q (Polq), we improve the targeted integration efficiency of linearized DNA fragments and single-strand oligonucleotides (ssODN) in mouse embryos and offspring. CasRX-assisted targeted integration (CATI) also leads to substantial improvements in HDR efficiency during the CRISPR/Cas9 editing of monkey embryos. We present a promising tool for generating monkey models and developing gene therapies for clinical trials.

MiRNA Expression Analysis of the Hippocampus in a Vervet Monkey Model of Fetal Alcohol Spectrum Disorder Reveals a Potential Role in Global mRNA Downregulation.

MicroRNAs (miRNAs) are short-length non-protein-coding RNA sequences that post-transcriptionally regulate gene expression in a broad range of cellular processes including neuro- development and have previously been implicated in fetal alcohol spectrum disorders (FASD). In this study, we use our vervet monkey model of FASD to follow up on a prior multivariate (developmental age × ethanol exposure) mRNA analysis (GSE173516) to explore the possibility that the global mRNA downregulation we observed in that study could be related to miRNA expression and function. We report here a predominance of upregulated and differentially expressed miRNAs. Further, the 24 most upregulated miRNAs were significantly correlated with their predicted targets (Target Scan 7.2). We then explored the relationship between these 24 miRNAs and the fold changes observed in their paired mRNA targets using two prediction platforms (Target Scan 7.2 and miRwalk 3.0). Compared to a list of non-differentially expressed miRNAs from our dataset, the 24 upregulated and differentially expressed miRNAs had a greater impact on the fold changes of their corresponding mRNA targets across both platforms. Taken together, this evidence raises the possibility that ethanol-induced upregulation of specific miRNAs might contribute functionally to the general downregulation of mRNAs observed by multiple investigators in response to prenatal alcohol exposure.

Tolerability and tropism of recombinant adeno-associated virus vectors in the African green monkey (Chlorocebus sabaeus) anterior chamber.

While many studies have investigated the use of recombinant adeno-associated vectors (rAAV) in the posterior chamber for treatment of inherited retinal diseases, fewer studies have looked at rAAV's ability to transduce cells within the anterior chamber. This study focuses on evaluating the tropism and tolerability of three rAAV serotypes-rAAV2/6, rAAV2/9, and rAAV2/2[MAX]-expressing a green fluorescent protein (GFP) reporter following intracameral injection in the non-human primate (NHP) African green monkey (Chlorocebus sabaeus) model. Injection of high dose (1 × 1012 vg/eye) rAAV vector resulted in transient inflammation characterized by aqueous flare and cellular infiltrate that resolved without intervention in all serotypes. Post-mortem histology revealed widespread expression of GFP in cells of the trabecular meshwork and iris in high dose rAAV2/6, rAAV2/9, and particularly rAAV2/2[MAX] eyes, indicating that rAAV vectors of these serotypes have broad tropism for cells of the anterior chamber and may facilitate the treatment of blinding disorders, such as glaucoma.

Bayesian predictive modeling of multi-source multi-way data

A Bayesian approach to predict a continuous or binary outcome from data that are collected from multiple sources with a multi-way (i.e., multidimensional tensor) structure is described. As a motivating example, molecular data from multiple 'omics sources, each measured over multiple developmental time points, as predictors of early-life iron deficiency (ID) in a rhesus monkey model are considered. The method uses a linear model with a low-rank structure on the coefficients to capture multi-way dependence and model the variance of the coefficients separately across each source to infer their relative contributions. Conjugate priors facilitate an efficient Gibbs sampling algorithm for posterior inference, assuming a continuous outcome with normal errors or a binary outcome with a probit link. Simulations demonstrate that the model performs as expected in terms of misclassification rates and correlation of estimated coefficients with true coefficients, with large gains in performance by incorporating multi-way structure and modest gains when accounting for differing signal sizes across the different sources. Moreover, it provides robust classification of ID monkeys for the motivating application.

Encapsulated Allografts Preclude Host Sensitization and Promote Ovarian Endocrine Function in Ovariectomized Young Rhesus Monkeys and Sensitized Mice.

Transplantation of allogeneic donor ovarian tissue holds great potential for female cancer survivors who often experience premature ovarian insufficiency. To avoid complications associated with immune suppression and to protect transplanted ovarian allografts from immune-mediated injury, we have developed an immunoisolating hydrogel-based capsule that supports the function of ovarian allografts without triggering an immune response. Encapsulated ovarian allografts implanted in naïve ovariectomized BALB/c mice responded to the circulating gonadotropins and maintained function for 4 months, as evident by regular estrous cycles and the presence of antral follicles in the retrieved grafts. In contrast to non-encapsulated controls, repeated implantations of encapsulated mouse ovarian allografts did not sensitize naïve BALB/c mice, which was confirmed with undetectable levels of alloantibodies. Further, encapsulated allografts implanted in hosts previously sensitized by the implantation of non-encapsulated allografts restored estrous cycles similarly to our results in naïve recipients. Next, we tested the translational potential and efficiency of the immune-isolating capsule in a rhesus monkey model by implanting encapsulated ovarian auto- and allografts in young ovariectomized animals. The encapsulated ovarian grafts survived and restored basal levels of urinary estrone conjugate and pregnanediol 3-glucuronide during the 4- and 5-month observation periods. We demonstrate, for the first time, that encapsulated ovarian allografts functioned for months in young rhesus monkeys and sensitized mice, while the immunoisolating capsule prevented sensitization and protected the allograft from rejection.

Cynomolgus-rhesus hybrid macaques serve as a platform for imprinting studies

Genomic imprinting can lead to allele-specific expression (ASE), where one allele is preferentially expressed more than the other. Perturbations in genomic imprinting or ASE genes have been widely observed across various neurological disorders, notably autism spectrum disorder (ASD). In this study, we crossed rhesus cynomolgus monkeys to produce hybrid monkeys and established a framework to evaluate their allele-specific gene expression patterns using the parental genomes as a reference. Our proof-of-concept analysis of the hybrid monkeys identified 353 genes with allele-biased expression in the brain, enabling us to determine the chromosomal locations of ASE clusters. Importantly, we confirmed a significant enrichment of ASE genes associated with neuropsychiatric disorders, including ASD, highlighting the potential of hybrid monkey models in advancing our understanding of genomic imprinting.

BCL6B Contributes to Ocular Vascular Diseases via Notch Signal Silencing

Endothelial cell activation is tightly controlled by the balance between VEGF (vascular endothelial cell growth factor) and Notch signaling pathway. VEGF destabilizes blood vessels and promotes neovascularization, which are common features of sight-threatening ocular vascular disorders. Here, we show that BCL6B (B-cell CLL/lymphoma 6 member B protein), also known as BAZF, ZBTB28, and ZNF62, plays a pivotal role in the development of retinal edema and neovascularization. The pathophysiological physiological role of BCL6B was investigated in cellular and animal models mimicking 2 pathological conditions: retinal vein occlusion and choroidal neovascularization. An in vitro experimental system was used in which human retinal microvascular endothelial cells were supplemented with VEGF. Choroidal neovascularization cynomolgus monkey model was generated to investigate the involvement of BCL6B in the pathogenesis. Mice lacking BCL6B or treated with BCL6B-targeting small-interfering ribose nucleic acid were examined for histological and molecular phenotypes. In retinal endothelial cells, the BCL6B expression level was increased by VEGF. BCL6B-deficient endothelial cells showed Notch signal activation and attenuated cord formation via blockage of the VEGF-VEGFR2 signaling pathway. Optical coherence tomography images showed that choroidal neovascularization lesions were decreased by BCL6B-targeting small-interfering ribose nucleic acid. Although BCL6B mRNA expression was significantly increased in the retina, BCL6B-targeting small-interfering ribose nucleic acid suppressed ocular edema in the neuroretina. The increase in proangiogenic cytokines and breakdown of the inner blood-retinal barrier were abrogated in BCL6B knockout (KO) mice via Notch transcriptional activation by CBF1 (C promotor-binding factor 1) and its activator, the NICD (notch intracellular domain). Immunostaining showed that Müller cell activation, a source of VEGF, was diminished in BCL6B-KO retinas. These data indicate that BCL6B may be a novel therapeutic target for ocular vascular diseases characterized by ocular neovascularization and edema.

Abstract 3923: Identification of membrane-expressed CAPRIN-1 as a novel and universal cancer target and generation of a therapeutic anti-CAPRIN-1 antibody TRK-950

Abstract Specific targets for cancer treatment are highly desirable, but still remain to be discovered. While previous reports suggested that CAPRIN-1 localizes in the cytoplasm, here we now show that part of this molecule is strongly expressed on the cell membrane surface in most solid cancers, but not normal tissues. Notably, the membrane expression of CAPRIN-1 extended to the subset of highly tumorigenic cancer stem cells and EMT induced metastatic cancer cells. In addition, we revealed that cancer cells with particularly high CAPRIN-1 surface expression exhibited enhanced tumorigenicity. We generated a therapeutic humanized anti-CAPRIN-1 antibody (TRK-950), which strongly and specifically binds to various cancer cells and shows anti-tumor effects via engagement of immune cells. TRK-950 was further developed as a new cancer drug and a series of pre-clinical studies demonstrates its therapeutic potency in a tumor bearing mouse model and safety in a relevant cynomolgus monkey model. Together our data demonstrate that CAPRIN-1 is a novel and universal target for cancer therapies. A phase I clinical study of TRK-950 (NCT02990481) has been completed and a phase Ib study (combination with approved drugs) is currently underway (NCT03872947). Citation Format: Fumiyoshi Okano, Takanori Saito, Yoshitaka Minamida, Shinichi Kobayashi, Takayoshi Ido, Yasushi Miyauchi, Ukei Wasai, Jiang Ke, Alexandra Aicher, Christopher Heeschen, Tetsu Yonehara. Identification of membrane-expressed CAPRIN-1 as a novel and universal cancer target and generation of a therapeutic anti-CAPRIN-1 antibody TRK-950. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3923.

New monkey embryo models-it's getting complicated.

Li etal.1 report on the generation of cynomolgus monkey models of blastocyst-stage embryos (called "blastoids") using naive cynomolgus embryonic stem cells. These blastoids recapitulate gastrulation invitro and induce early pregnancy responses when transferred into cynomolgus monkey surrogates, prompting consideration of the policy implications for human blastoid research.

Microarrays, Enzymatic Assays, and MALDI-MS for Determining Specific Alterations to Mitochondrial Electron Transport Chain Activity, ROS Formation, and Lipid Composition in a Monkey Model of Parkinson’s Disease

Multiple evidences suggest that mitochondrial dysfunction is implicated in the pathogenesis of Parkinson's disease via the selective cell death of dopaminergic neurons, such as that which occurs after prolonged exposure to the mitochondrial electron transport chain (ETC) complex I inhibitor, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrine (MPTP). However, the effects of chronic MPTP on the ETC complexes and on enzymes of lipid metabolism have not yet been thoroughly determined. To face these questions, the enzymatic activities of ETC complexes and the lipidomic profile of MPTP-treated non-human primate samples were determined using cell membrane microarrays from different brain areas and tissues. MPTP treatment induced an increase in complex II activity in the olfactory bulb, putamen, caudate, and substantia nigra, where a decrease in complex IV activity was observed. The lipidomic profile was also altered in these areas, with a reduction in the phosphatidylserine (38:1) content being especially relevant. Thus, MPTP treatment not only modulates ETC enzymes, but also seems to alter other mitochondrial enzymes that regulate the lipid metabolism. Moreover, these results show that a combination of cell membrane microarrays, enzymatic assays, and MALDI-MS provides a powerful tool for identifying and validating new therapeutic targets that might accelerate the drug discovery process.

Evaluation of therapeutic effects of tetramethylpyrazine nitrone in Alzheimer's disease mouse model and proteomics analysis.

The pathophysiology of Alzheimer's disease (AD) is multifactorial with characteristic extracellular accumulation of amyloid-beta (Aβ) and intraneuronal aggregation of hyperphosphorylated tau in the brain. Development of disease-modifying treatment for AD has been challenging. Recent studies suggest that deleterious alterations in neurovascular cells happens in parallel with Aβ accumulation, inducing tau pathology and necroptosis. Therefore, therapies targeting cellular Aβ and tau pathologies may provide a more effective strategy of disease intervention. Tetramethylpyrazine nitrone (TBN) is a nitrone derivative of tetramethylpyrazine, an active ingredient from Ligusticum wallichii Franchat (Chuanxiong). We previously showed that TBN is a potent scavenger of free radicals with multi-targeted neuroprotective effects in rat and monkey models of ischemic stroke. The present study aimed to investigate the anti-AD properties of TBN. We employed AD-related cellular model (N2a/APPswe) and transgenic mouse model (3×Tg-AD mouse) for mechanistic and behavioral studies. Our results showed that TBN markedly improved cognitive functions and reduced Aβ and hyperphosphorylated tau levels in mouse model. Further investigation of the underlying mechanisms revealed that TBN promoted non-amyloidogenic processing pathway of amyloid precursor protein (APP) in N2a/APPswe in vitro. Moreover, TBN preserved synapses from dendritic spine loss and upregulated synaptic protein expressions in 3×Tg-AD mice. Proteomic analysis of 3×Tg-AD mouse hippocampal and cortical tissues showed that TBN induced neuroprotective effects through modulating mitophagy, MAPK and mTOR pathways. In particular, TBN significantly upregulated PINK1, a key protein for mitochondrial homeostasis, implicating PINK1 as a potential therapeutic target for AD. In summary, TBN improved cognitive functions in AD-related mouse model, inhibited Aβ production and tau hyperphosphorylation, and rescued synaptic loss and neuronal damage. Multiple mechanisms underlie the anti-AD effects of TBN including the modulation of APP processing, mTOR signaling and PINK1-related mitophagy.

Assessment of brain imaging and cognitive function in a modified rhesus monkey model of depression

Depression incurs a huge personal and societal burden, impairing cognitive and social functioning and affecting millions of people worldwide. A better understanding of the biological basis of depression could facilitate the development of new and improved therapies. Rodent models have limitations and do not fully recapitulate human disease, hampering clinical translation. Primate models of depression help to bridge this translational gap and facilitate research into the pathophysiology of depression. Here we optimized a protocol for administering unpredictable chronic mild stress (UCMS) to non-human primates and evaluated the influence of UCMS on cognition using the classical Wisconsin General Test Apparatus (WGTA) method. We used resting-state functional MRI to explore changes in amplitude of low-frequency fluctuations and regional homogeneity in rhesus monkeys. Our work highlights that the UCMS paradigm effectively induces behavioral and neurophysiological (functional MRI) changes in monkeys but without significantly impacting cognition. The UCMS protocol requires further optimization in non-human primates to authentically simulate changes in cognition associated with depression.

A long-acting anti-IL-8 antibody improves inflammation and fibrosis in endometriosis.

Current pharmacological treatments for endometriosis are limited to hormonal agents that can relieve pain but cannot cure the disease. Therefore, the development of a disease-modifying drug for endometriosis is an unmet medical need. By studying human endometriotic samples, we found that the progression of endometriosis was associated with the development of inflammation and fibrosis. In addition, IL-8 expression was highly up-regulated in endometriotic tissues and closely correlated with disease progression. We created a long-acting recycling antibody against IL-8 (AMY109) and evaluated its clinical potency. Because rodents do not produce IL-8 and do not experience menstruation, we analyzed the lesions in cynomolgus monkeys that spontaneously developed endometriosis and in a surgically induced endometriosis monkey model. Both spontaneously developed and surgically induced endometriotic lesions demonstrated pathophysiology that was highly similar to that of human endometriosis. Once-a-month subcutaneous injection of AMY109 to monkeys with surgically induced endometriosis reduced the volume of nodular lesions, lowered the Revised American Society for Reproductive Medicine score as modified for monkeys, and ameliorated fibrosis and adhesions. In addition, experiments using cells derived from human endometriosis revealed that AMY109 inhibited the recruitment of neutrophils to endometriotic lesions and the production of monocyte chemoattractant protein-1 from neutrophils. Thus, AMY109 may represent a disease-modifying therapy for patients with endometriosis.