Sphingomyelin synthase 2 promotes the stemness of breast cancer cells via modulating NF-κB signaling pathway.

OBJECTIVES: Multi-drug resistance (MDR) to chemotherapy is the main obstacle influencing the anti-tumor effect in breast cancer, which might lead to the metastasis and recurrence of cancer. Until now, there are still no effective methods that can overcome MDR. In this study, we aimed to investigate the role of sphingomyelin synthase 2 (SMS2) in breast cancer resistance. METHODS: Quantitative RT-PCR analysis was performed to assess changes in mRNA expression. Western blot analysis was performed to detect protein expression. Inhibitory concentration value of adriamycin (ADR) was evaluated using CCK 8 assay. The stemness ability of breast cancer cells was assessed by spheroid-formation assay. Immunofluorescence staining was conducted to show the cellular distribution of proteins. Breast tumor masses were harvested from the xenograft tumor mouse model. RESULTS: SMS2 overexpression increased the IC50 values of breast cancer cells. SMS2 decreased the CD24 transcription level but increased the transcription levels of stemness-related genes including CD44, ALDH, OCT 4 and SOX2 in breast cancer cells. SMS2 overexpression promoted the nuclear translocation of phosphorylated NF-κB, while suppression of SMS2 could inhibit the NF-κB pathway. CONCLUSIONS: SMS2 increased the stemness of breast cancer cells via NF-κB signaling pathway, leading to resistance to the chemotherapeutic drug ADR. Thus, SMS2 might play a critical role in the development of breast cancer resistance, which is a previously unrecognized mechanism in breast cancer MDR development.

Head-to-head comparison of cone-beam breast computed tomography and mammography in the diagnosis of primary breast cancer: A systematic review and meta-analysis.

INTRODUCTION: To compare the diagnostic performance of cone-beam breast computed tomography (CBBCT) and mammography (MG) in primary breast cancer. METHODS: PubMed, Embase, Web of Science, China National Knowledge Infrastructure, WanFang DATA, and China Science and Technology Journal databases were searched comprehensively from inception to March 2023. Sensitivity and specificity were calculated using bivariate random-effects models, and a summary receiver operating characteristic (SROC) curve was constructed. Bivariate I2 statistics and meta-regression analyses were also performed. The differences in diagnostic performance between CBBCT and MG were analysed using Z-test statistics. Clinical utility was explored using Fagan's nomogram, and quality assessment was conducted utilising the Quality Assessment of Diagnostic Accuracy Studies-2 checklist. RESULTS: The summary sensitivity and specificity for CBBCT in diagnosing primary breast cancer were 0.92 (95 % CI: 0.87-0.94) and 0.79 (95 % CI: 0.71-0.85), respectively, and the area under the curve (AUC) of the SROC was 0.93 (95 % CI: 0.90-0.95). For MG, the summary sensitivity and specificity were 0.77 (95 % CI: 0.69-0.83) and 0.75 (95 % CI: 0.66-0.82), respectively, with an AUC of 0.83 (95 % CI: 0.80-0.86). The Z-test revealed that the summary sensitivity of CBBCT was significantly higher than that of MG (P < 0.001). Additionally, the summary AUC of CBBCT was significantly higher than that of MG (P < 0.001). CONCLUSION: The diagnostic performance of CBBCT for primary breast cancer was better than that of MG. However, the results of both the CBBCT and MG are based on studies with small sample sizes. Further studies with larger sample sizes and more comprehensive designs are required to address this issue.

Application of HER2 peptide vaccines in patients with breast cancer: a systematic review and meta-analysis.

BACKGROUND: The E75 and GP2 vaccines are the few therapeutic vaccines targeting HER2 currently under clinical research for patients with breast cancer. METHODS: Databases, including the Cochrane Library, PubMed, Medline, Embase, and Web of Science, were used to retrieve clinical studies on E75 and GP2 vaccines. Retrieval time was from the beginning of database construction until May 31st, 2021. RESULTS: A total of 24 clinical studies were included in this analysis, including 1704 patients in the vaccinated group and 1248 patients in the control group. For the E75 vaccine, there were significant differences between the vaccinated group and the control group in the delayed-type hypersensitivity reaction (SMD = 0.685 95% CI 0.52-0.85, PHeterogeneity = 0.186, PDTH < 0.05) and the change in CD8+ T-cell numbers (SMD = - 0.864, 95% CI - 1.02 to - 0.709, PHeterogeneity = 0.085, PCD8+ T cell < 0.05) before and after injection. For the GP2 vaccine, there was a significant difference between the vaccinated group and the control group in the change in CD8+ T-cell numbers (SMD = - 0.584, 95% CI - 0.803 to - 0.294, PHeterogeneity = 0.397, PCD8+ T cell < 0.05) before and after injection. In addition, the clinical outcomes, including recurrence rate (RR = 0.568, 95% CI 0.444-0.727, PHeterogeneity = 0.955, PRecurrence < 0.05) and disease-free survival rate (RR = 1.149, 95% CI 1.050-1.256, PHeterogeneity = 0.003, PDFS < 0.05), of the E75-vaccinated group were different from those of the control group. However, we found that the overall survival rate with the E75 vaccine (RR = 1.032, 95% CI 0.998-1.067, PHeterogeneity = 0.476, POS > 0.05) was not different between the two groups. Local and systemic toxicity assessments of the two vaccines showed minimal side effects. CONCLUSIONS: The E75 vaccine was effective and safe in patients with breast cancer. The GP2 vaccine could elicit a strong immune response, but more trials are needed to confirm its clinical efficacy.

Maxims nudge equitable or efficient choices in a Trade-Off Game.

The core problem in the distribution dilemma is the trade-off between equity and efficiency. With the development of socio-economic conditions, the optimal decision changes between equitable and efficient options. The methods for nudging decision-makers to make optimal decisions without changing the event are extremely important. This study used two laboratory behavior experiments to explore the impact of maxim information on the trade-off between equity and efficiency. The study explores whether stake levels and division schemes affect the nudging effect of the maxim in a Trade-Off Game (TOG). We found that participants were affected by maxim information in decision-making scenarios, and participants showed different equity preferences as the maxim information changed, without relevance of the stake level. Additionally, the nudging effect of the maxim only exists under the condition that the distributor's interests is not affected.

Three-dimensional visualization technique in endoscopic breast-conserving surgery and pedicled omentum for immediate breast reconstruction.

PURPOSE: To evaluate the three-dimensional visualization technique (3DVT) in endoscopic breast-conserving surgery (EBCS) and pedicled omentum for immediate breast reconstruction. METHODS: Clinical data of 256-slice multi-detector CT scanning from 52 patients (group A) were introduced into self-developed Medical Imaging 3D Visualization Systems (MI-3DVS) for individualized segmentation, 3D reconstruction and volume calculation. The surgical process was designed according to the 3D model. Next, the EBCS and pedicled omentum breast reconstruction were performed according to the preoperative design. Finally, the operating time, blood loss, length of postoperative hospital stay, complications and cosmetic outcomes in group A were compared to 44 patients in group B, who underwent the same operation without 3DVT. RESULTS: The 3DVT can be used to analyze the location of the breast tumors and determine the excision extension of the breast precisely. Compared to group B, group A had the advantage of less bleeding, shortened operating time and earlier discharge (p < 0.05). The cosmetic results of group A were more satisfactory than those of group B (p < 0.05). After a postoperative follow-up of 6-30 months, none of the patients in either group showed any signs of recurrence. CONCLUSIONS: 3DVT can be used to design the surgical process preoperatively and results in positive therapeutic and cosmetic outcomes in EBCS and pedicled omentum for immediate breast reconstruction.

Sphingomyelin synthase 2 promotes an aggressive breast cancer phenotype by disrupting the homoeostasis of ceramide and sphingomyelin.

Breast cancer is the most common type of carcinoma in women worldwide, but the mechanisms underlying tumour development and progression remain unclear. Sphingomyelin synthase 2 (SGMS2) is a crucial regulator involved in ceramide (Cer) and sphingomyelin (SM) homoeostasis that is mostly studied for its role in lipid metabolism. Our primary study indicated that high SGMS2 expression is associated with breast cancer metastasis. Gain- and loss-of-function assays in vitro and in vivo revealed that SGMS2 promotes cancer cell proliferation by suppressing apoptosis through a Cer-associated pathway and promotes cancer cell invasiveness by enhancing epithelial-to-mesenchymal transition (EMT) initiation through the TGF-ß/Smad signalling pathway. Further study determined that SGMS2 activated the TGF-ß/Smad signalling pathway primarily by increasing TGF-ß1 secretion, which was likely associated with aberrant expression of SM. Thus, our findings indicate that SGMS2-mediated activation of the TGF-ß/Smad signalling pathway is important in breast cancer progression, which provides new insight into the mechanisms underlying breast cancer metastasis and suggests a possible anticancer therapy for breast cancer.

[Application of 3D visualization technique in breast cancer surgery with immediate breast reconstruction using laparoscopically harvested pedicled latissimus dorsi muscle flap].

OBJECTIVE: To study the value of 3D visualization technique in breast-preserving surgery for breast cancer with immediate breast reconstruction using laparoscopically harvested pedicled latissimus dorsi muscle flap. METHODS: From January, 2015 to May, 2016, 30 patients with breast cancer underwent breast-preserving surgery with immediate breast reconstruction using pedicled latissimus dorsi muscle flap. The CT data of the arterial phase and venous phase were collected preoperatively and imported into the self-developed medical image 3D visualization system for image segmentation and 3D reconstruction. The 3D models were imported into the simulation surgery platform for virtual surgery to prepare for subsequent surgeries. The cosmetic outcomes of the patients were evaluated 6 months after the surgery. Another 18 patients with breast cancer who underwent laparoscopic latissimus dorsi muscle breast reconstruction without using 3D visualization technique from January to December, 2014 served as the control group. The data of the operative time, intraoperative blood loss and postoperative appearance of the breasts were analyzed. RESULTS: The reconstructed 3D model clearly displayed the anatomical structures of the breast, armpit, latissimus dorsi muscle and vessels and their anatomical relationship in all the 30 cases. Immediate breast reconstruction was performed successfully in all the cases with median operation time of 226 min (range, 210 to 420 min), a median blood loss of 95 mL (range, 73 to 132 mL). Evaluation of the appearance of the breast showed excellent results in 22 cases, good appearance in 6 cases and acceptable appearance in 2 cases. In the control group, the median operation time was 283 min (range, 256 to 313 min) and the median blood loss was 107 mL (range, 79 to 147 mL) with excellent appearance of the breasts in 10 cases, good appearance in 4 cases and acceptable appearance in 4 cases. CONCLUSION: 3D reconstruction technique can clearly display the morphology of the latissimus dorsi and the thoracic dorsal artery, allows calculation of the volume of the breast and the latissimus dorsi, and helps in defining the scope of resection of the latissimus dorsi to avoid injuries of the pedicled vessels. This technique also helps to shorten the operation time, reduce intraoperative bleeding, and improve the appearance of the reconstructed breast using pedicled latissimus dorsi muscle flap.

Immediate liposuction could shorten the time for endoscopic axillary lymphadenectomy in breast cancer patients.

BACKGROUND: Endoscopic axillary lymphadenectomy (EALND) was introduced to clinical work to reduce side effects of conventional axillary lymphadenectomy, while the lipolysis and liposuction of EALND made the process consume more time. The aim of the study was to determine whether immediate liposuction after tumescent solution injection to the axilla could shorten the total time of EALND. METHODS: Fifty-nine patients were enrolled in the study, 30 of them received EALND with traditional liposuction method (TLM), and the rest 29 patients received EALND with immediate liposuction method (ILM). The operation time, cosmetic result, drainage amount, and hospitalization time of the two groups were compared. RESULTS: The median EALND operation time of TLM group and ILM group were 68 and 46 min, respectively, the difference was significant (P < 0.05); the median cosmetic results of the two groups were 6.6 and 6.4, respectively; the median drainage amount of the two groups were 366 and 385 ml, respectively; the hospitalization time of the two groups were 15 and 16 days, respectively. For the last three measures, no significant difference was confirmed (P > 0.05). CONCLUSIONS: Our work suggests immediate liposuction could shorten the endoscopic axillary lymphadenectomy process, and this method would not compromise the operation results. However, due to the limitations of the research, more work needs to be done to prove the availability and feasibility of immediate liposuction.

[Application of digital 3D technique combined with nanocarbon-aided navigation in endoscopic sentinel lymph node biopsy for breast cancer].

OBJECTIVE: To study the clinical value of digital 3D technique combined with nanocarbon-aided navigation in endoscopic sentinel lymph node biopsy for breast cancer. METHODS: Thirty-nine female patients with stage I/II breast cancer admitted in our hospital between September 2014 and September 2015 were recruited. CT lymphography data of the patients were segmented to reconstruct digital 3D models, which were imported into FreeForm Modeling Surgical System Platform for visual simulation surgery before operation. Endoscopic sentinel lymph node biopsy and endoscopic axillary lymph node dissection were then carried out, and the accuracy and clinical value of digital 3D technique in endoscopic sentinel lymph node biopsy were analyzed. RESULTS: s The 3D models faithfully represented the surgical anatomy of the patients and clearly displayed the 3D relationship among the sentinel lymph nodes, axillary lymph nodes, axillary vein, pectoralis major, pectoralis minor muscle and latissimus dorsi. In the biopsy, the detection rate of sentinel lymph nodes was 100% in the patients with a coincidence rate of 87.18% (34/39), a sensitivity of 91.67% (11/12), and a false negative rate of 8.33% (1/12). Complications such as limb pain, swelling, wound infection, and subcutaneouseroma were not found in these patients 6 months after the operation. CONCLUSION: Endoscopic sentinel lymph node biopsy assisted by digital 3D technique and nanocarbon-aided navigation allows a high detection rate of sentinel lymph nodes with a high sensitivity and a low false negative rate and can serve as a new method for sentinel lymph node biopsy for breast cancer.

Epigenetic silencing of miR-490-3p promotes development of an aggressive colorectal cancer phenotype through activation of the Wnt/ß-catenin signaling pathway.

The Wnt/ß-catenin pathway is known to contribute to colorectal cancer (CRC) progression, although little is known about the contribution of ß-catenin on this process. We investigated the role of miR-490-3p, which was recently reported to suppress tumorigenesis through its effect on Wnt/ß-catenin signaling. We found that hypermethylation of the miR-490-3p promoter down-regulates miR-490-3p expression in CRC tissue. Gain- and loss-of-function assays in vitro and in vivo reveal that miR-490-3p suppresses cancer cell proliferation by inducing apoptosis and inhibits cell invasiveness by repressing the initiation of epithelial-to-mesenchymal transition (EMT), a key mechanism in cancer cell invasiveness and metastasis. The frequently rearranged in advanced T-cell lymphomas (FRAT1) protein was identified as a direct target of miR-490-3p and contributes to its tumor-suppressing effects. miR-490-3p appears to have an inhibitory effect on ß-catenin expression in nuclear fractions of CRC cells, whereas FRAT1 expression is associated with the accumulation of ß-catenin in the nucleus of cells, which could be weakened by transfection with miR-490-3p. Our findings suggest that the miR-490-3p/FRAT1/ß-catenin axis is important in CRC progression and provides new insight into the molecular mechanisms underlying CRC. They may help to confirm the pathway driving CRC aggressiveness and serve for the development of a novel miRNA-targeting anticancer therapy.

The sirtuin 3 expression profile is associated with pathological and clinical outcomes in colon cancer patients.

AIM: To investigate the correlation between Sirtuin 3 (SIRT3) expression and the clinical outcome of patients with colon cancer. METHODS: The tumor specimens from 127 patients with colon cancer were obtained for SIRT3 immunohistochemical staining. Patients were followed up. In in vitro study, SIRT3 gene was inhibited to observe the effects of SIRT3 on the biological behavior of cultured colon cells. RESULTS: The SIRT3 expression level was found to be significantly associated with the lymph node metastasis (P < 0.001) and tumor stages (P < 0.001). The colon cancer-specific survival was 64.6% among patients with high SIRT3 expressions and 88.6% among patients with low SIRT3 expressions (log-rank P = 0.016). The overall survival was 80.2% among patients with low SIRT3 expressions and 55.9% among patients with high SIRT3 expressions (log-rank P = 0.002). In vitro study showed that silencing of SIRT3 gene inhibited the proliferation, invasion, and cells migration but increased the apoptosis in the cultured colon cell lines. CONCLUSION: This study provides evidence supporting that SIRT3 is closely associated with the clinical outcomes of colon cancer. SIRT3 may be considered as a marker for colon cancer.

[Screening molecular markers in early breast cancer of the same pathological types but with different prognoses using Agilent gene chip].

OBJECTIVE: To screen molecular markers in early breast cancer and establish gene subtyping-based diagnostic criteria for predicting the prognosis of early breast cancers. METHODS: Tumor tissue specimens were obtained from 8 patients with early breast cancer for analysis of the differentially expressed genes using Agilent custom 8×15 000 chips in combination with the prognostic data of the patients. Another 42 tumor tissue specimens were used to validate the differential genes by real-time fluorescent quantitative PCR. RESULTS: Gene microarray analysis identified 132 differentially expressed genes between the patients with favorable and poor prognosis, and 44 of these genes were significantly up-regulated (by over two folds) and 88 down-regulated in patients with poor prognoses. CONCLUSION: The gene expression profiles differ in early breast cancer tissues of the same pathological type but with different clinical stages and prognoses, and CD44, MKI67, NTRK2, Nek2, C16orf60, TOP2A, ANCCA, and RRM2 genes can be used as the prognostic markers for early breast cancer.

Axonal and glial responses to a mid-thoracic spinal cord hemisection in the Macaca fascicularis monkey.

A comprehensive understanding of the pathology of spinal cord injury (SCI) in non-human primates may facilitate greatly the development of new strategies to promote recovery in humans with SCI. Relatively few studies, however, have been conducted to systemically examine pathological changes in the monkey, a non-human primate, after SCI. We report axonal, glial, and fibrotic responses in the spinal cord of monkey Macaca fascicularis after a thoracic (T) 8-9 lateral hemisection. We examined these changes at three regions--i.e., the lesion epicenter, the peri-lesion area, and the lateral white matter of the intact, contralateral hemicord at 7 (subacute) and 30 (early chronic) days post-injury. The lateral hemisection resulted in a marked axon and myelin loss, along with tissue loss, at the lesion epicenter at both time points. Unexpectedly, axonal loss and myelin degeneration, along with reactive gliosis and microglia/macrophages activation, were also observed in the contralateral spared hemicord, indicating a spread of the initial damage to the contralateral side. In addition, activated microglia/macrophages were found both within the injury epicenter and the peri-lesion area, indicating that they participate in injury-induced immune responses that may exacerbate the secondary damage. In contrast to rodents, substantial reactive astrocytic responses at the lesion border were not observed in the monkey. Conversely, a deposit of robust fibrotic scar was observed at the injury epicenter, which filled the space originally created by the hemisection. Thus, understanding the pathology of monkey SCI may provide clinically relevant information in designing repair strategies targeting specific problems associated with human SCIs.

[Preliminary study on simulating sensory nerves of intestinal contents using ultrasound detecting system].

Successful assessing intestinal lumen content with ultrasound signals might lay a strong basis for the development of the artificial anal sphincter. In the present study, we utilized a modified MLU02-212 ultrasonic gas bubble detector to test the distal part of proximal colon in each rabbit, for the group of twenty healthy New Zealand rabbits. Voltage signals of solid, liquid, gas and empty content of the lumen were collected and compared. The results indicated that there were significant differences among the voltage signals in the 4 conditions (P = 0.000), respectively. Multiple comparison showed significant differences existed in any pair of the four conditions (P = 0.000). Three signal non-overlapping regions existed in these 4 conditions. Thus it seemed that ultrasound could be utilized to distinguish various contents inside the intestinal lumen and could act as "artificial sensory nerve".

[Colonic sac duct for first-stage repair of colon anastomotic leakage in miniature pigs].

OBJECTIVE: To study the efficacy, safety and reliability of colonic sac duct for first-stage repair of colorectal anastomotic leakage. METHODS: An animal model of colon anastomotic leakage was established in 30 Tibet miniature pigs, which were randomly divided into treatment group and control group (n=15). Colon anastomotic leakage in the treatment group was repaired using the colonic sac duct, while the control group received conventional surgical repair. At 7, 14, and 21 days after the surgery, the healing of the anastomotic leakage was evaluated by examining the bursting pressure, tissue microvessel density and hydroxyproline content at the anastomosis. RESULTS: Using the colonic sac duct, the anastomotic leakage was successfully repaired without death of the pigs or the occurrence of intestinal stenosis or necrosis. At 7 and 14 days after the surgery, the bursting pressure, hydroxyproline contents, and microvessel density in the treatment groups were higher than those in the control group, but such difference was not found at 21 days. CONCLUSION: Colonic sac duct allows effective repair of colon anastomotic leakage, and is especially useful for leakage lasting for 48-72 h complicated by severe abdominal infection.

In vitro and in vivo assessment of an intelligent artificial anal sphincter in rabbits.

Artificial sphincters have been developed for patients with fecal incontinence, but finding a way to make such sphincters more "intelligent" remains a problem. We assessed the function of a novel intelligent artificial anal sphincter (IAAS) in vitro and in vivo in rabbits. After the prosthesis was activated, rabbits were continent of feces during 81.4% of the activation time. The fecal detection unit provided 100% correct signals on stool in vitro and 65.7% in vivo. The results indicated that the IAAS could efficiently maintain continence and detect stool; however, the IAAS is still in the preliminary experimental stage and more work is needed to improve the system.

Proteolytic processing of angiopoietin-like protein 4 by proprotein convertases modulates its inhibitory effects on lipoprotein lipase activity.

Angiopoietin-like protein 4 (ANGPTL4) has been associated with a variety of diseases. It is known as an endogenous inhibitor of lipoprotein lipase (LPL), and it modulates lipid deposition and energy homeostasis. ANGPTL4 is cleaved by unidentified protease(s), and the biological importance of this cleavage event is not fully understood with respect to its inhibitory effect on LPL activity. Here, we show that ANGPTL4 appears on the cell surface as the full-length form, where it can be released by heparin treatment in culture and in vivo. ANGPTL4 protein is then proteolytically cleaved into several forms by proprotein convertases (PCs). Several PCs, including furin, PC5/6, paired basic amino acid-cleaving enzyme 4, and PC7, are able to cleave human ANGPTL4 at a consensus site. PC-specific inhibitors block the processing of ANGPTL4. Blockage of ANGPTL4 cleavage reduces its inhibitory effects on LPL activity and decreases its ability to raise plasma triglyceride levels. In summary, the cleavage of ANGPTL4 by these PCs modulates its inhibitory effect on LPL activity.

Selective reduction in the sphingomyelin content of atherogenic lipoproteins inhibits their retention in murine aortas and the subsequent development of atherosclerosis.

OBJECTIVE: We used the sphingomyelin (SM) synthase 2 (Sms2) gene knockout (KO) approach to test our hypothesis that selectively decreasing plasma lipoprotein SM can play an important role in preventing atherosclerosis. METHODS AND RESULTS: The sphingolipid de novo synthesis pathway is considered a promising target for pharmacological intervention in atherosclerosis. However, its potential is hampered because the substance's atherogenic mechanism is not completely understood. We prepared Sms2 and apolipoprotein E (Apoe) double-KO mice. They showed a significant decrease in plasma lipoprotein SM levels (35%, P<0.01) and a significant increase in ceramide and dihydroceramide levels (87.5% and 27%, respectively; P<0.01) but no significant changes in other tested sphingolipids, cholesterol, and triglyceride. Non-high-density lipoproteins from the double-KO mice showed a reduction of SM, but not cholesterol, and displayed less tendency toward aortic sphingomyelinase-mediated lipoprotein aggregation in vitro and retention in aortas in vivo when compared with controls. More important, at the age of 19 weeks, Sms2 KO/Apoe KO mice showed a significant reduction in atherosclerotic lesions of the aortic arch and root (52%, P<0.01) compared with controls. The Sms2 KO/Apoe KO brachiocephalic artery contained significantly less SM, ceramide, free cholesterol, and cholesteryl ester (35%, 32%, 58%, and 60%, respectively; P<0.01) than that of the Apoe KO brachiocephalic artery. CONCLUSIONS: Decreasing plasma SM levels through decreasing SMS2 activity could become a promising treatment for atherosclerosis.

Glial response and myelin clearance in areas of wallerian degeneration after spinal cord hemisection in the monkey Macaca fascicularis.

Spinal cord injury (SCI) in mammals not only damages the focal area, but also leads to wallerian degeneration (WD) of axons and myelin distal to the injury. In the present study, we investigated cellular responses within areas of WD of a sensory pathway, the fasciculus gracilis, after a T8-9 lateral spinal hemisection in the adult monkey Macaca fascicularis. Spinal cord segments rostral and caudal to the injury at two clinically-relevant time points, 1 week and 4 weeks post-SCI, representing subacute and chronic stages, respectively, were examined. We observed marked axon degeneration in the areas of WD at the subacute stage, and minimal axonal neurofilament staining at the chronic stage. At the ultrastructural level, however, many degenerating axonal profiles remained at the chronic stage. Myelin breakdown was a much-delayed process. A large number of residual myelin sheaths was observed at the chronic stage. In contrast to rodents, a substantial astrogliotic response was not found in the WD regions up to 4 weeks post-injury. Microglia activation was evident in the WD areas at the subacute stage, and was enhanced at the chronic stage. However, the lack of round reactive microglia/macrophages in these regions suggests that microglial activation was either delayed or incomplete. Thus it appears that many pathological characteristics of WD in monkeys are much delayed compared to those in rodents, but are similar to those in humans. Our results suggest that non-human primate SCI models are useful for evaluating repair strategies before they are translated to clinical trials of human SCI.