Abstract
Nonhuman primates are used extensively in a variety of nonclinical safety evaluation studies of new drugs. In those studies, intravenous infusion is a common treatment method, a noninvasive telemetry system is usually used for cardiovascular safety and pharmacology evaluation, and blood samples are repeatedly collected for various analysis. Intravenous infusion, vest wearing, and repeated intravenous blood collection can caused a stress response in cynomolgus monkeys, which may lead to changes in clinical pathology parameters in them. Here, we aimed to test the effects of the above operations on clinical pathology parameters in cynomolgus monkeys. Twenty monkeys (10 male/10 female) were administered 0.9% sodium chloride injections via intravenous infusions on Days 1 and 10. Each animal wore a vest before each dosing, and the vest was removed at 24 h after each dosing. Blood samples were collected before the first dose and at 2 min, 24 h, 48 h, 72 h, and 168 h after each dosing. As compared to values before the first dose (D-1) increases in reticulocytes (percentage and absolute count) and decreases in erythrocytes (red blood cells, hemoglobin, and hematocrit) were noted after dosing. The decrease in erythrocytes and increase in reticulocytes were considered to the related to the repeated intravenous blood collection. Increases in leukocytes (white blood cells and absolute count and percentage of neutrophils) and platelets (mean platelet volume and platelet distribution width) were noted at 2 min or 24 h post dose. Increases in aspartate aminotransferase, direct bilirubin, creatine kinase, C-reactive protein, and human cardiac troponin I and decreases in inorganic phosphate were noted at 2 min to 72 h post dose.
Keywords: clinical pathology, cynomolgus monkeys, repeated intravenous blood collection, vest
Introduction
The cynomolgus monkey is accepted by health authorities worldwide as an appropriate non-rodent species for drug safety evaluations. In those evaluations, intravenous infusion is a widely used administration method, and blood samples are repeatedly collected for various analyses, such as toxicokinetics [1], immunogenicity analysis [2], and receptor occupancy analysis [3] in pharmacological and toxicological studies. In the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) S7A Guideline, a noninvasive telemetry system is recommended for cardiovascular safety and pharmacology evaluation. Data from unrestrained animals that may be chronically instrumented for telemetry, other suitable instrumentation methods for conscious animals, or animals conditioned to the laboratory environment are preferable to data from restrained or unconditioned animals [4]. However, intravenous infusion, vest wearing, and repeated intravenous blood collection can caused a stress response in cynomolgus monkeys. It is well known that stress (such as anesthesia, repeated intravenous blood collection, and transportation) results in relatively high plasma cortisol levels and white blood cell counts and low red blood cell counts in many primates [5,6,7,8,9]. Thus, understanding the factors that contribute to stressors in monkeys can have a significant impact on the interpretation of study results.
In the present study, we investigated the effects of the intravenous infusion, vest wearing, and repeated bleeding on hematology parameters, clinical chemistry parameters, C-reactive protein (CRP), and human cardiac troponin I (hsTnI) in cynomolgus monkeys. CRP and hsTnI were evaluated in this study because CRP is an extremely sensitive indicator of the acute phase reaction, and hsTnI is a specific indicator for evaluating cardiotoxicity in toxicity studies.
Materials and Methods
Experimental animals
All procedures were conducted in compliance with all applicable sections of the “Guide for the Care and Use of Laboratory Animals” (2011) issued by the US National Research Council; “Laboratory Animal Administration” (2017) issued by the State Science and Technology Committee, People’s Republic of China; and “Laboratory Animal Administration Regulations” (1997) issued by the Shanghai Laboratory Animal Administration Office, P. R. China. The animals were managed at Shanghai InnoStar Bio-tech Co., Ltd., an accredited animal facility, complying with the AAALAC International animal care policies. All procedures involving the care and use of laboratory animals in the study were reviewed and approved by the Institutional Animal Care and Use Committee (IACUC) of the testing facility.
Healthy cynomolgus monkeys (12 males and 12 females; age, 2.57 ± 0.01 years; body weight, 2.3 ± 0.25 kg) were used in this study. Pre-test health screening data, including cage-side observations, hematology, coagulation, clinical chemistry, CRP, and hsTnI, were analyzed by a veterinarian and the study director, and 20 (10 males and 10 females) monkeys were selected for this study. The monkeys were group housed in stainless steel cages (800 × 900 × 890 mm) with a 12-h light/dark cycle (which started at 7:00 a.m. and ended at 7:00 p.m. every day) in a controlled temperature (18–26°C) and humidity (40–70%) environment in compliance with the “Guide for the Care and Use of Laboratory Animals”. All animals were placed in individual cages in the morning before they were fed and returned to group housing after any remaining food was withdrawn. Filtered 100% fresh air (no air recirculation) was used with at least 9 air changes per h. Monkeys were fed once daily in the morning with banana/apple (approximately 90 g/animal/day) and Lab Monkey Maintenance Diet (approximately 160 g/animal/day) supplied by the Beijing Keao-Xieli Feed Co., Ltd. (Beijing, China), and the remaining food was withdrawn after 4 p.m. Monkeys were provided ad libitum access to deionized water produced in house.
Administration and vest wearing
Monkeys were placed in a monkey chair administered a 0.9% sodium chloride injection (Anhui Double-Crane Pharmaceutical Co., Ltd., Wuhu, China; lot No. 2102012C) via intravenous infusion on Days 1 (D1) and 10 (D10) without anesthesia (Table 1). Considering the recovery of red blood cells, the time of the second administration was adjusted from D8 to D10 because the mice had not yet recovered from the decrease in red blood cells (RBCs) by 168 h post dose on D1. The dose volume was 10 ml/kg, the dose rate was 2 ml/min.
Table 1. Work schedule.
| Day | Procedure |
|---|---|
| D –1 | Blood collection, vest wearing for each animal |
| D1 | First administration, blood collection at 2 min and 2 h post dose on D1 |
| D2 | vest removal, blood collection at 24 h post dose on D1 |
| D3 | Blood collection at 48 h post dose on D1 |
| D4 | Blood collection at 72 h post dose on D1 |
| D8 | Blood collection at 168 h post dose on D1 |
| D9 | Vest wearing for each animal |
| D10 | Second administration, blood collection at 2 min and 2 h post dose on D10 |
| D11 | Vest removal, blood collection at 24 h post dose on D10 |
| D12 | Blood collection at 48 h post dose on D10 |
| D13 | Blood collection at 72 h post dose on D10 |
| D17 | Blood collection at 168 h post dose on D10 |
The monkeys used in this experiment were not implanted with telemetric transmitters. Each animal was sedated with propofol (intravenous injection, 6–9 mg/kg; Sichuan Guorui Pharmaceutical Co., Ltd., Leshan, China; lot No. 1811161) and wore a vest on D −1 and D9, and the vest was removed at 24 h after each dosing (D2 and D11; Table 1).
Blood collection and processing
The abbreviations, units, and analysis methods for parameters are presented in Table 2. Animals were fasted overnight. The animals were placed in a monkey chair to collect blood without anesthesia and were not trained for blood sampling. Blood samples were collected from the femoral vein or peripheral veins of the four limbs before the first dose (D −1) and at 2 min ± 1 min (D1 and D10), 2 h ± 10 min (D1 and D10), 24 h ± 10 min (D2 and D11), 48 h ±15 min (D3 and D12), 72 h ± 15 min (D4 and D13), and 168 h ± 30 min (D8 and D17) post dose on D1 and D10 (Table 1). The blood collection time was determined based on the end time of the intravenous injection. Approximately 2 ml of blood was collected per animal at each time point. Samples for hematology analysis were collected into tubes containing EDTA-K2 as an anticoagulant and were analyzed by a Sysmex XN-1000V Automated Hematology Analyzer.
Table 2. Parameters and analytical methods.
| Hematology and coagulation parameters | Unit | Abbreviation | Analytical method |
|---|---|---|---|
| Red blood cell | 10^6/μl | RBC | Hematocyte counter |
| Hemoglobin | g/dl | HGB | Hematocyte counter |
| Hematocrit | % | HCT | Hematocyte counter |
| Mean corpuscular volume | fl | MCV | Hematocyte counter |
| Mean corpuscular hemoglobin | pg | MCH | Hematocyte counter |
| Mean corpuscular hemoglobin concentration | g/dl | MCHC | Hematocyte counter |
| Reticulocyte percentage | % | RET% | Hematocyte counter |
| Reticulocyte, absolute | 10^9/l | RET# | Hematocyte counter |
| Red cell distribution width | % | RDW-CV | Hematocyte counter |
| Platelet count | 10^3/μl | PLT&O | Hematocyte counter |
| Mean platelet volume | fL | MPV | Hematocyte counter |
| Platelet distribution width | fL | PDW-SD | Hematocyte counter |
| Platelets crit | % | PCT | Hematocyte counter |
| White blood cell | 10^3/μl | WBC | Hematocyte counter |
| Neutrophils (absolute) | 10^3/μl | NEUT# | Hematocyte counter |
| Lymphocytes (absolute) | 10^3/μl | LYMPH# | Hematocyte counter |
| Monocytes (absolute) | 10^3/μl | MONO# | Hematocyte counter |
| Eosinophils (absolute) | 10^3/μl | EO# | Hematocyte counter |
| Basophils (absolute) | 10^3/μl | BASO# | Hematocyte counter |
| Neutrophils percentage | % | NEUT% | Hematocyte counter |
| Lymphocytes percentage | % | LYMPH% | Hematocyte counter |
| Monocytes percentage | % | MONO% | Hematocyte counter |
| Eosinophils percentage | % | EO% | Hematocyte counter |
| Basophils percentage | % | BASO% | Hematocyte counter |
| Alanine aminotransferase | U/l | ALT | Kinetic |
| Aspartate aminotransferase | U/l | AST | Kinetic |
| Alkaline phosphatase | U/l | ALP | Kinetic |
| Creatine kinase | U/l | CK | Kinetic |
| Gamma glutamyl transpeptidase | U/l | GGT | Kinetic |
| Total cholesterol | mmol/l | CHOL | OX |
| Triglyceride | mmol/l | TG | GPO-HDAOS |
| Total bilirubin | μmol/l | TBIL | Vanadate OX |
| Bilirubin, direct | μmol/l | DBIL | Vanadate OX |
| Glucose | mmol/l | GLU | G-6-PDH |
| Urea nitrogen | mmol/l | BUN | GIDH |
| Creatinine | μmol/l | CREA | HMMPS |
| Sodium | mmol/l | Na | ISE |
| Potassium | mmol/l | K | ISE |
| Chloride | mmol/l | Cl | ISE |
| Calcium | mmol/l | Ca | MXB |
| Inorganic phosphate | mmol/l | P | ADM-UV |
| Total protein | g/l | TP | Biuret |
| Albumin | g/l | ALB | BCG |
| Globulin | g/l | GLO | Calculated |
| Albumin/globulin ratio | N/A | A/G | Calculated |
| C-reactive protein | mg/l | CRP | Immunoturbidimetry |
| Human cardiac troponin I | ng/ml | hsTnI | Immunoassays |
Samples for clinical chemistry and CRP analysis were collected into tubes with separation gel and coagulant and were centrifuged at approximately 4,000 rpm for 10 min at 4°C to obtain serum. Serum samples were analyzed by a Hitachi 7180 Clinical Analyzer.
Samples for hsTnI analysis were collected into the tubes with separation gel and coagulant and were centrifuged at approximately 4,000 rpm for 10 min at 4°C to obtain serum. Serum samples were analyzed by an ACCESS 2 immunoassay system. The analysis of hsTnI using monkey serum was performed in a validated manner for monkeys, and the data were not nonspecific values.
Data analysis and statistics
Data was analyzed using IBM SPSS Statistics 21. Group means and standard deviations were calculated by sex for hematology, clinical chemistry, CRP, and hsTnI. Percentage change after treatment was calculated by the following formula: (mean post-dose time point value-mean pre-first dose value)/mean pre-first dose value × 100. Comparisons between the post-dose values and pre-first dose values were performed using the following statistical methods: Data within groups were evaluated for homogeneity of variance by Levene’s test. For data with homogeneous variances (P>0.05), a one-way analysis of variance (ANOVA) was performed on the data; for nonhomogeneous data (P≤0.05), a logarithmic transformation was automatically applied to obtain log data, and a Levene’s test was applied to the log data again. For log data with homogeneous variances (P>0.05), one-way ANOVA was performed on the log data; for nonhomogeneous log data (P≤0.05), a rank transformation was applied on the log data to obtain rank data, and then the Kruskal-Wallis test was performed. Differences between post-dose values and pre-first dose values were further tested by Dunnett’s test for pairwise comparisons (at the 0.05 and 0.01 levels) when the results of ANOVA were significant (P≤0.05). Otherwise, no further analyses were performed. When significant results were obtained in the Kruskal-Wallis test (P≤0.05), Dunnett’s test was used on rank data for pairwise comparisons between post-dose values and pre-first dose values (at the 0.05 and 0.01 levels). When no significant results were obtained in the Kruskal-Wallis test (P>0.05), no further analyses were performed.
Results
Hematology analysis
As compared with the D −1 values, statistically significant increases in leukocytes (white blood cells, WBCs; absolute count and percentage of neutrophils, NEUT# and NEUT%), platelets (mean platelet volume, MPV; platelet distribution width, PDW), and reticulocytes (absolute count and percentage of reticulocytes, RET% and RET#) and decreases in erythrocytes were noted after dosing (Tables 3 and 4 , Figs. 1 and 2). Decreases in red blood cells (RBCs; ↓8.21–23.26%), hemoglobin (HGB; ↓8.06–24.45%), and hematocrit (HCT; ↓6.09–23.26%) were noted in males and females after dosing on D1 and D10. Increases in RET% (↑71.73–442.71%) and RET# (↑48.68–309.42%) were noted in males and females after dosing on D1 (except at 2 min and 2 h on D1) and D10. Increases in WBCs (↑84.58–167.89%), NEUT# (↑193.32–460.20%), and NEUT% (↑53.95–102.50%) were noted in males and females at 2 h post dose on D1 and 24 h post dose on D10. Increases in WBCs (↑100.39%), NEUT# (↑146.36%), and NEUT% (↑50.92%) were noted in females at 2 min post dose on D10. An increases in PDW (↑30.16%) was noted in males at 24 h post dose on D10, and increases in MPV (↑15.84–20.89%) were noted in males at 2 h and 24 h post dose on D10.
Table 3. Effects on hematology parameters in females (n=10).
Table 4. Effects on hematology parameters in males (n=10).
Fig. 1.
Changes in reticulocytes and erythrocytes in males and females after dosing. (A) Changes in RBCs, HGB, and HCT in females (n=10). (B) Changes in RBCs, HGB, and HCT in males (n=10). (C) Changes in RET% and RET# in females (n=10). (D) Changes in RET% and RET# in males (n=10). M, male; F, female.
Fig. 2.
Changes in leukocytes in males and females after dosing. (A) Changes in WBCs, NEUT#, and NEUT% in females (n=10). (B) Changes in WBCs, NEUT#, and NEUT% in males (n=10). (C) Changes in LYMPH% and MONO% in females (n=10). (D) Changes in LYMPH% and MONO% in males (n=10). M, male; F, female.
Decreases in lymphocyte and monocyte percentages (LYMPH% and MONO%) were noted in males and females at 2 h post dose on D1 and 24 h post dose on D10. However, no decreases in absolute lymphocytes and monocytes (LYMPH# and MONO#) were noted, and the above changes were considered to be caused by the increased NEUT% (Figs. 2A–D).
All other statistically significant changes were small in magnitude and considered to be due to biological variations.
Clinical chemistry analysis
As compared with the D −1 values, statistically significant increases in aspartate aminotransferase (AST), total bilirubin (TBIL), and creatine kinase (CK) and/or decreases in inorganic phosphate (P) were noted after dosing (Tables 5 and 6, Fig. 3). Increases in AST (↑55.61–345.11%) were noted in females at 2 min and 72 h post dose on D1 and in males and females at 2 h and 24 h post dose on D1 and D10. Increases in TBIL (↑34.25–73.37%) were noted in males and females at 2 h post dose on D1 and D10 and in males at 24 h post dose on D1. Decreases in P (↓19.89–19.95%) were noted in females at 2 min and 24 h post dose on D1. An increase in P was noted in males at 2 min post dose on D10. Increases in CK (↑231.90–1,049.80%) were noted in males and females at 2 h and 24 h post dose on D1 and 2 h post dose on D10, in females at 72 h post dose on D1, and in males at 72 h post dose on D10.
Table 5. Effects on clinical chemistry parameters in females (n=10).
Table 6. Effects on clinical chemistry parameters in males (n=10).
Fig. 3.
Changes in clinical chemistry in males and females after dosing. (A) Changes in AST (n=10). (B) Changes in TBIL (n=10). (C) Changes in P (n=10). (D) Changes in CK (n=10). M, male; F, female.
All other statistically significant changes were small in magnitude and considered to be due to biological variations.
CRP analysis
Compared with the D −1 values, an increase in CRP (↑527.98%) was noted in females at 24 h post dose on D1 (Table 7). Furthermore, an increase in CRP was noted in females (↑256.42%) at 24 h post dose on D10 compared with the D −1 values, but the increase was not significant (Fig. 4).
Table 7. Effects on CRP (n=10).
| CRP (mg/dl) |
||
|---|---|---|
| Females | Males | |
| D-1 | 2.18 ± 1.26 | 2.53 ± 1.62 |
| 2 min post dose on D1 | 4.57 ± 2.86 | 3.37 ± 2.85 |
| 2 h post dose on D1 | 4.74 ± 2.86 | 3.45 ± 2.81 |
| 24 h post dose on D1 | 13.69 ± 7.83* | 5.74 ± 5.03 |
| 72 h post dose on D1 | 4.12 ± 2.12 | 1.75 ± 1.15 |
| 168 h post dose on D1 | 2.98 ± 1.44 | 2.3 ± 1.65 |
| 2 min post dose on D10 | 2.85 ± 1.78 | 2.92 ± 1.96 |
| 2 h post dose on D10 | 3.08 ± 1.88 | 2.92 ± 1.91 |
| 24 h post dose on D10 | 7.77 ± 8.45 | 4.26 ± 2.68 |
| 72 h post dose on D10 | 4.34 ± 5.08 | 2.29 ± 1.4 |
| 168 h post dose on D10 | 4.76 ± 5.33 | 2.24 ± 1.27 |
Data presented are arithmetic mean values ± SD. *P≤0.05 compared with the D-1 values.
Fig. 4.
Changes in CRP in males and females after dosing (n=10). M, male; F, female.
HsTnI Analysis
Compared with the D −1 values, increases in hsTnI were noted in 1/20 monkeys (Animal no. 115, 0.1501 pg/ml) at 2 min post dose on D1, in 3/20 monkeys (animal no. 108: 0.2396 pg/ml, animal no.1010, 0.1259 pg/ml; animal no. 115: 0.1501 pg/ml) at 2 h post dose on D1, in 1/20 monkeys (animal no.108, 0.1129 pg/ml) at 24 h post dose on D1, in 3/20 monkeys (animals no. 11, 0.1373 pg/ml) at 168 h post dose on D1, and in 2/20 monkeys (animals no, 108, 0.1231 pg/ml; and animal no. 115, 0.1373 pg/ml) at 2 h post dose on D10 (Fig. 5).
Fig. 5.
Individual data for hsTnI (n=20).
Discussion
In drug safety evaluation studies, intravenous infusion is a widely used administration method, sampling blood multiple times is necessary to assess toxicokinetic profiles or immunogenicity, and cardiovascular and respiratory examinations are often performed in studies involving cynomolgus monkeys [1,2,3,4]. Intravenous infusion, vest wearing, and repeated intravenous blood collection can be stressors for cynomolgus monkeys. Monkeys are reported to be susceptible to various kinds of stress, which can lead to changes in behavior and hormones [5,6,7, 10,11,12]. Understanding the effects of intravenous infusion, vest wearing, and repeated intravenous blood collection on physiological indicators in animals is helpful for researchers to distinguish the effects of a test article and stress in toxicological studies, which is of great significance for evaluating the potential toxicity of a test article.
The hematological reaction to stress characterized hematologically by leukocytosis and hemoconcentration has been shown to be attenuated in rhesus monkeys habituated to sampling procedures [13]. In our study, increases in leukocytes and reticulocytes and decreases in erythrocytes were noted in males and females after dosing, as compared with the D −1 values. At the same time point, the decreases in RBCs, HGB, and HCT and increases in WBCs, NEUT#, NEUT%, RET%, and RET# in females were greater than those in males (Figs. 1A–D and Figs.2A and B). As compared with the D −1 values, an increase in platelets (MPV and PDW) was noted in males after dosing but not in females after dosing. Decreases in RBCs were more obvious as the number of blood collection times increased. Thus, the loss of erythrocytes was considered to be related to the repeated intravenous blood collection (Figs. 1A and B). The standard model of erythropoiesis starts with hematopoietic stem cells in the bone marrow, giving rise to multipotent progenitors that go on to erythroid-committed precursors to mature RBCs and the reticulocytes complete their maturation within 1–2 days [14]. Thus, the rebound of the RBCs and HCT in females at 72 h post dose on D1 and the rebound of the RBCs, HCT, and HGB in males and females at 2 min and 168 h post dose on D10 were due to the newborn reticulocytes differentiating into mature erythrocytes (Figs. 1A–D).
Neutrophils are very short-lived cells and die by apoptosis within 24 h of leaving the bone marrow [15, 16]. The apoptosis of neutrophils can be inhibited by cortisol and synthetic glucocorticoids [17]. Stress conditions stimulates the adrenal medulla and adrenal cortex to secrete catecholamine and glucocorticoids respectively [18]. In our study, increases in WBCs, NEUT#, and NEUT% were noted in males and females at 2 h post dose on D1 and 24 h post dose on D10 and in females at 2 min post dose on D1. These findings indicated that the intravenous infusion, vest wearing, and blood collection were stressful for the animals and the above changes were considered to be related to the effects of stress on the animals. This suggests that researchers need to comprehensively determine whether these changes within 24 h of administration are related to the article or caused by stress stimulation in toxicity studies.
Blood sampling has been shown to cause fear-grinning, vocalizations, diarrhea, and physical resistance (e.g., struggling, refusing to enter a squeeze cage) in nonhuman primates [19]. It has been reported that transport stimulation can increase AST and TBIL levels in cynomolgus monkeys [20], and it is well known that stress causes CK to rise. In our study, as compared with the D −1 values, increases in AST, TBIL, and CK were noted in animals after dosing. The increase of AST in females was greater than that in males, and the duration of the increase in females was longer than that in males, these results indicate that females are more sensitive than males in terms of AST level (Fig. 3A). The increases of AST, TBIL, and CK and the decrease of P in the first dosing cycle were greater than those in the second dosing cycle, which indicates that after repeated administration, animals gradually adapted to intravenous administration, vest wearing, and blood collection (Figs. 3A, B, and D). In our study, decreased P was noted in females at 2 min and 24 h post dose on D1, and increased P was noted in males at 2 min post dose on D10 (Fig. 3C). Further research is needed to clarify the role of P in stressed animals.
CRP is an acute phase reactive protein, with concentrations increasing substantially and quickly in response to acute inflammation or trauma. Following acute phase stimulation, the CRP level may increase 100- or even 500-fold [21]. Furthermore, a trend of higher CRP has been noted in rhesus monkeys with early social stress [22]. In our study, compared with the D −1 values, increases in CRP were noted in females at 24 h post dose on D1 (↑527.98%) and D10 (↑256.42%). Furthermore, a trend toward increased CRP was noted in males at 24 h post dose on D1 (↑126.88%) and D10 (↑68.38%), but the increased proportion of CRP in males was obviously lower than those in females (Fig. 4). These results indicate that females are more sensitive than males in terms of CRP level. The increases of CRP in the first dosing cycle were greater than those in the second dosing cycle, which indicates that after repeated administration, animals gradually adapted to intravenous administration, vest wearing, and blood collection.
The use of hsTnI to predict the potential cardiotoxicity of a test article in toxicological studies is growing rapidly. An association between elevated stress hormone concentrations and troponin T analysis was found by a highly sensitive method in healthy study participants [23]. However, the authors of the present study emphasize that the role of psychoemotional stress in the pathophysiology of cardiomyocyte damage needs to be further studied [24]. In our study, compared with the D −1 values, increases in hsTnI (>0.1 pg/ml) were noted in individual monkeys at 2 min to 24 h and 168 h post dose on D1 and at 2 h post dose on D10 (Fig. 5). Furthermore, the increases in hsTnI induced by stress showed significant individual differences. This suggests that we should pay attention to the increase in hsTnI level of individual animals in drug safety evaluation studies. If a transient increase in hsTnI is noted in only a few animals during a study with no accompanied abnormal findings observed in electrocardiograms and histopathological examinations, stress should be considered as the possible cause of the increase in hsTnI.
In this study, the effects of intravenous infusion, vest wearing, and repeated intravenous blood collection on hematology parameters, clinical chemistry parameters, CRP, and hsTnI were evaluated in cynomolgus monkeys. As compared with the D −1 values, increases in WBCs, NEUT#, NEUT%, MPV, PDW, RET%, RET#, AST, TBIL, CK, CRP, and hsTnI and decreases in RBCs, HGB, HCT, and P were noted after dosing. Based on these results, it is important to establish a vehicle control group in experimental studies, and the concept of ‘normal’ should be discussed. Researchers should be rational when referring to published reference values. Ideally, research institutions should establish and update their own background databases. In this study, the effects of combined intravenous administration, vest wearing, and repeated intravenous blood collection in cynomolgus monkeys were described for the first time. This study represents fundamental research. The results can not only be helpful for the various types of experimental research at test facilities but also serve the fundamental research in the experimental animal industry and provide reliable fundamental research data for scientific researchers in the same industry.
Conflict of Interest
The authors declare no conflict of interest associated with this study.
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