[C2 pedicle screw insertion assisted by mobilization of the vertebral artery in cases with high-riding vertebral artery]

Objective: To examine the feasibility, safety, and efficacy of mobilization of the vertebral artery for C2 pedicle screws in cases with high-riding vertebral artery (HRVA). Methods: The clinical data of 12 patients with basilar invagination and atlantoaxial dislocation underwent atlantoaxial reduction and fixation in the Department of Neurosurgery, the First Affiliated Hospital of University of Science and Technology of China between January 2020 and November 2021 were retrospectively analyzed. All patients had high-riding vertebral artery on at least one side that prohibited the insertion of C2 pedicle screws. There were 2 males and 10 females aged (48.0±12.8) years (range: 17 to 67 years). After correction of vertical dislocation during the operation, the C2 pedicle screw insertion and occipitocervical fixation and fusion were performed using the vertebral artery mobilization technique. Neurological function was assessed using the Japanese Orthopedic Association (JOA) scale. The preoperative and postoperative JOA score and the main radiological measurements, including the anterior atlantodental interval (ADI), the distance of the odontoid tip above the Chamberlain line, the clivus-canal angle, were collected and compared by paired t-test. Results: Mobilization of the high-riding vertebral artery was successfully completed, and C2 pedicle screws were then fulfilled after the vertebral artery was protected. There was no injury to the vertebral artery during the operation. Meanwhile, no severe surgical complications such as cerebral infarction or aggravated neurological dysfunction occurred during the perioperative period. Satisfactory C2 pedicle screw placement and reduction were achieved in all 12 patients. All patients achieved bone fusion 6 months after surgery. No looseness and shift in internal fixation or reduction loss was observed during the follow-up period. Compared to the preoperative, the postoperative ADI decreased from (6.1±1.9) mm to (2.0±1.2) mm (t=6.73, P<0.01), the distance of the odontoid tip above the Chamberlain line decreased from (10.4±2.5) mm to (5.5±2.3) mm (t=7.12, P<0.01), the clivus-canal angle increased from (123.4±11.1) ° to (134.7±9.6) ° (t=2.50, P=0.032), the JOA score increased from 13.3±2.1 to 15.6±1.2 (t=6.99, P<0.01). Conclusion: The C2 pedicle screw insertion assisted by mobilization of the vertebral artery is safe and considerably effective, providing a choice for internal fixation in cases with high-riding vertebral arteries.

Agminated spitz nevi: case report and review of the literature

Spitz nevi are benign melanocytic lesions with many histologic similarities to malignant melanoma. A case of agminated Spitz nevi on a 2-year-old boy's left cheek is reported and 41 other cases of agminated Spitz nevi are reviewed. In this case, two biopsies were performed on two different-appearing lesions and the results of both biopsies showed Spitz nevi.

Organogenesis of pancreatic anlagen allografted in rats

AIMS

To study the possibility of revascularization, growth, and differentiation of embryonic pancreatic anlagen transplanted to adult hosts. While transplantations of pancreas and islets are the main methods to cure diabetes mellitus, the donor source is in shortage. So it's necessary to find a new source for transplantation.

METHODS

The pancreas from embryonic day 14.5 (E14.5) and 15.5 (E15.5) Lewis rat embryos were implanted into either intraperitoneal or subrenal capsular site of healthy Lewis rats. at 3 weeks or 6 weeks after implantation, the pancreatic anlagen in the host rats were resected for size measurements, as well as histopathologic and immunohistochemical examinations.

RESULTS

Three weeks after implantation into the renal-capsular site, the size of both E14.5 and E15.5 pancreatic anlagen had enlarged 10- to 15-fold with differentiation of acinar components upon histological examination. Moreover, increasing numbers of beta cells and islets stained positive for insulin, and newly generated vessels were observed around the tissues. Continued proliferation of the endocrine islets in E14.5 pancreatic anlagen grafts was observed after another 3 weeks, whereas further proliferation in the E15.5 pancreatic anlagen graft was not seen. Additionally fibrosis appeared in the exocrine component of both E14.5 and E15.5 pancreatic anlagen at this time point. When implanted into intraperitoneal site, enlarged E15.5 pancreatic anlagen with proliferatels beta cells were also observed after 3 weeks. However, both the size of the pancreatic anlagen and the proliferation of the beta cells were much less than that in the subrenal capsular site.

CONCLUSIONS

The allografted E14.5 and E15.5 pancreatic anlagen revascularised and grew into tissues that were structurally similar to normal mature rats pancreatic tissue. Adequate embryonic age for the transplantation of pancreatic anlagen is 14.5 and 15.5 days old. Subrenal capsula is a more suitable site than the peritoneal cavity for implantation of pancreatic anlagen.

A Study of Soluble HLA-G1 Protecting Porcine Endothelial Cells Against Human Natural Killer Cell-Mediated Cytotoxicity

Human natural killer (NK) cells, which can mediate direct lysis of porcine endothelial cells, play an important role in xenograft rejection. HLA-G, which is a critical molecule in maintaining maternal immune tolerance of semi-allogenic fetus, is able to protect susceptible target cells from lysis induced by NK cells. In this study, we investigated whether soluble HLA-G1 (sHLA-G1) protected porcine xenogeneic cells against human NK cell-mediated lysis.

METHODS

The human sHLA-G1 genomic DNA (pcDNA3-sHLA-G1) was transfected into a B lymphoblastoid cell line 721.221 (LCL721.221) by nucleofector. The sHLA-G1 expression of the transfected LCL721.221 cells was identified by RT-PCR and Dot-ELISA. The sHLA-G1 protein was purified by affinity chromatography on anti-HLA-ImAb W6/32 coupled to cyanogen-bromide-activated Sepharose 4B from culture supernates of transfectants. Various concentrations of sHLA-G(1) protein (0, 2, 4, 6, or 8 microg/mL) were added to a NK cell-mediated xenogenic cell lysis system with either NK92 cells or fresh human peripheral blood mononuclear cells (PBMCs) cocultured with the porcine endothelial cells line. A LDH release assay was used to evaluate NK cell-mediated cytotoxicity.

RESULTS

sHLA-G1 provided significant protection of porcine endothelial cells against human NK-mediated cytotoxicity in a dose-dependent manner. The rates of NK92 cell-mediated cytotoxicity were reduced to 83.4 +/- 5.7% (2 microg/mL), 56.6 +/- 9.3% (4 microg/mL), 39.3 +/- 10.2% (6 microg/mL), and 31.2 +/- 4.9% (8 microg/mL) versus 96.9 +/- 3.0% in the control group (P < .01). Similarly, adding 6 microg/mL sHLA-G1 reduced the mean rate of PBMC-mediated cytotoxicity (n = 4) to 5.8 +/- 1.6% from 23.9 +/- 1.3% in the control group (P < .01).

CONCLUSIONS

These results indicated that sHLA-G1 protected xenogeneic porcine endothelial cells against attack by human NK cells, thus providing a new approach to overcome NK-mediated immunity to xenografts.

Sertoli Cells Induce Xenolymphocyte Apoptosis In Vitro

BACKGROUND

Testicular Sertoli cells can protect pancreatic islet grafts from allo- and autoimmune destruction; however, the mechanisms underlying immune privilege of the testicle are not well understood, especially in xenotransplantation. The purpose of this study was to investigate whether rat Sertoli cells could induce mouse lymphocyte apoptosis in vitro.

METHODS

Testis was isolated from 2- to 4-week-old Sprague Dawley (SD) rats. Sertoli cells were successfully prepared by digestion with collagenase type V, trypsin, and DNase I, and then identified by electron microscope. Viability and apoptosis of cultured cells were measured by flow cytometry. We examined the apoptosis rates of Balb/c mouse lymphocytes, which were cocultured with SD rat Sertoli cells by FACS. The expression of Fas ligand (Fasl), transforming growth factor (TGF)-beta1 and clusterin on Sertoli cells were detected by immunocytochemistry.

RESULTS

In the cocultured system, Sertoli cells accounted for more than 93%. With our isolation method, the viability of Sertoli cells was more than 95% and the apoptosis rate was 10.87% +/- 3.87%. The lymphocyte apoptosis ratio was 15.52 +/- 0.17 (P < .01, compared with the control groups). SABC immunochemistry staining showed that the sertoli cells could express FasL, TGF-beta, and clusterin.

CONCLUSIONS

In our coculture in vitro, rat Sertoli cells expressed FasL and TGF-beta1 as well as induced the apoptosis of mouse lymphocytes. These results indicated that the expression of FasL and TGF-beta1 on Sertoli cells might relate to immune privilege in xenotransplantation.