Comparison Between Corticocancellous Allograft and Bovine Xenograft for Sinus Augmentation: A Radiographic, Histologic, and Histomorphometric Clinical Study.

Sinus floor augmentation is one of the most common approaches to obtain sufficient bone availability for placing implants in cases with severe bone atrophy in the posterior maxilla. Several bone substitutes are indicated for sinus augmentation, but they may achieve different clinical outcomes. This study aims to compare bovine bone mineral (BBM) with freeze-dried bone allograft (FDBA) in a two-stage lateral window sinus grafting approach. Twenty patients received a lateral window sinus elevation with either FDBA or BBM. Postoperative graft height was measured with CBCT. Implants were placed 6 months later, at which time biopsy samples were taken for histologic analysis and new CBCT scans were performed to measure graft height. The mean height reduction at 6 months was 20.27% ± 4.94% for FDBA samples and 5.36% ± 2.41% for BBM samples. The histologic analysis revealed a mean ratio of newly formed bone of 43.70% ± 5.29% for the FDBA group and 38.11% ± 4.03% for the BBM group. The FDBA group also showed a higher amount of residual biomaterial (17.25% ± 10.10%) and connective tissue (14.63% ± 4.38%) compared to the BBM group (15.53% ± 5.42% and 13.11% ± 4.42%, respectively). The differences between groups were statistically significant for the height reduction and newly formed bone (P ≤ .05) but not for the amounts of residual biomaterial and nonmineralized connective tissue (P ≥ .05). Six months after performing a lateral window sinus elevation, the percentage of newly formed bone was significantly higher when using FDBA than when using BBM, although the graft height reduction was also significantly higher for the FDBA group.

Survival analysis of dental implants placed in horizontally severely resorbed maxillae after reconstruction with xenogeneic graft: a case series.

PURPOSE: To evaluate the survival rates of dental implants with a hybrid macrostructure and the surface biomimetically coated with nanohydroxyapatite, placed in horizontally atrophic maxillae previously submitted to the guided bone regeneration (GBR) procedure, associated with the use of a deproteinized bovine bone graft (DBB). METHODS: Twenty-five patients who received 196 implants were involved in this study. First, these patients were submitted to GBR procedures and maxillary sinus lift, where DBB was used as the grafting material. The dental implants were placed after a minimum period of 6 months of the grafting procedures. The patients were followed up every six months and clinical/radiographic examinations were performed to assess the implants, using the following indicators as a reference: (1) Absence of mobility; (2) Absence of pain. Data about the age, surgery time, smoking status, implant size, and time between the grafting procedure and implant placement were correlated with implant failures. RESULTS: Twelve implants failed, generating a survival rate of 94.23%. None of the variables analysed correlated with the implant failures. CONCLUSION: Implants with a hybrid macrostructure and surface biomimetically coated with nanohydroxyapatite present good survival rates in horizontally atrophic maxillae grafted with DBB.

Establishment of an orthotopic prostate cancer xenograft mouse model using microscope-guided orthotopic injection of LNCaP cells into the dorsal lobe of the mouse prostate.

BACKGROUND: Orthotopic LNCaP xenograft mouse models closely mimic the progression of androgen-dependent prostate cancer in humans; however, orthotopic injection of LNCaP cells into the mouse prostate remains a challenge. METHODS: Under the guidance of a stereoscopic microscope, the anatomy of the individual prostate lobes in male Balb/c athymic nude mice was investigated, and LNCaP cells were inoculated into the mouse dorsal prostate (DP) to generate orthotopic tumors that mimicked the pathophysiological process of prostate cancer in humans. Real-time ultrasound imaging was used to monitor orthotopic prostate tumorigenesis, contrast-enhanced ultrasonography (CEUS) was used to characterize tumor angiogenesis, and macroscopic and microscopic characteristics of tumors were described. RESULTS: The DP had a trigonal bipyramid-shape and were located at the base of the seminal vesicles. After orthotopic inoculation, gray scale ultrasound imaging showed progressive changes in tumor echotexture, shape and location, and tumors tended to protrude into the bladder. After 8 weeks, the tumor take rate was 65% (n = 13/20 mice). On CEUS, signal intensity increased rapidly, peaked, and decreased gradually. Observations of gross specimens showed orthotopic prostate tumors were well circumscribed, round, dark brown, and soft, with a smooth outer surface and a glossy appearance. Microscopically, tumor cells were arranged in acini encircled by fibrous septa with variably thickened walls, mimicking human adenocarcinoma. CONCLUSIONS: This study describes a successful approach to establishing an orthotopic LNCaP xenograft Balb/c athymic nude mouse model. The model requires a thorough understanding of mouse prostate anatomy and proper technique. The model represents a valuable tool for the in vivo study of the biological processes involved in angiogenesis in prostate cancer and preclinical evaluations of novel anti-angiogenic therapies.

Reconstruction of the orbital floor using supercritical CO2 decellularized porcine bone graft.

Orbital floor fractures subsequently lead to consequences such as diplopia and enophthalmos. The graft materials used in orbital floor fractures varied from autografts to alloplastic grafts, which possess certain limitations. In the present study, a novel porcine bone matrix decellularized by supercritical CO2 (scCO2), ABCcolla® Collagen Bone Graft, was used for the reconstruction of the orbital framework. The study was approved by the institutional review board (IRB) of Kaohsiung Medical University Chung-Ho Memorial Hospital (KMUH). Ten cases underwent orbital floor reconstruction in KMUH in 2019. The orbital defects were fixed by the implantation of the ABCcolla® Collagen Bone Graft. Nine out of ten cases used 1 piece of customized ABCcolla® Collagen Bone Graft in each defect. The other case used 2 pieces of customized ABCcolla® Collagen Bone Graft in one defect area due to the curved outline of the defect. In the outpatient clinic, all 10 cases showed improvement of enophthalmos on CT (computerized tomography) at week 8 follow-up. No replacement of implants was needed during follow-ups. To conclude, ABCcolla® Collagen Bone Graft proved to be safe and effective in the reconstruction of the orbital floor with high accessibility, high stability, good biocompatibility, low infection rate and low complication rate.

How common are complications following polypropylene mesh, biological xenograft and native tissue surgery for pelvic organ prolapse? A secondary analysis from the PROSPECT trial.

OBJECTIVE: To report complication rates following prolapse surgery using polypropylene mesh inlay, polypropylene mesh kit, biological collagen xenografts and native tissue repairs. DESIGN: Secondary analysis of the PROSPECT randomised controlled trial and cohort study. SETTING: Thirty-five UK hospitals. POPULATION: A total of 2632 women undergoing anterior and/or posterior vaginal prolapse repair. METHODS: Event rates were calculated for all complications. Analysis was by treatment received. MAIN OUTCOME MEASURES: IUGA/ICS classification of complications and validated patient reported outcome measures. RESULTS: At baseline, 8.4% of women had 'generic' pain/discomfort; at 2 years following surgery, there was an improvement in all four groups; however, 3.0% of women developed de novo extreme generic pain. At 24 months de novo vaginal tightness occurred in 1.6% of native tissue, 1.2% of biological xenograft, 0.3% of mesh inlay and 3.6% of mesh kit. Severe dyspareunia occurred in 4.8% of native tissue, 4.2% of biological xenograft, 3.4% of mesh inlay repairs and 13.0% of mesh kits. De novo severe dyspareunia occurred in 3.5% of native tissue, 3.5% of biological xenograft, 1.4% of mesh inlays and 4.8% of mesh kits. Complications requiring re-admission to hospital, unrelated to mesh, affected 1 in 24 women; the most common reasons for re-admission were vaginal adhesions, urinary retention, infection and constipation. CONCLUSIONS: This is the first study to address the complications of vaginal mesh used for prolapse surgery alongside data from both native tissue and biological xenograft. It demonstrates the complexity of assessing pain and that all types of prolapse surgery have low surgical morbidity and a low rate of severe complications. TWEETABLE ABSTRACT: A prospective study of 2362 women undergoing vaginal mesh, xenograft or native tissue repair found low surgical morbidity and low rates of severe complications.

Establishment and characterization of an ovarian yolk sac tumor patient-derived xenograft model.

OBJECTIVE: The lack of appropriate preclinical models of ovarian yolk sac tumor (OYST) is currently hindering the pursuit of new methods of treatment and investigation of the pathogenesis of the disease. We developed and characterized an OYST patient-derived xenograft (PDX) model in this study. METHODS: Tumor fragments from a patient with an OYST were implanted subcutaneously into BALB/c Nude mice. Engrafted xenografts were compared with the original tumor according to histology, immunohistochemistry, humanized identified, and drug efficacy testing with in vivo treatment programs. RESULTS: There was a high degree of histologic and immunohistochemical (IHC) resemblance between the established PDX model and its corresponding human tumors. Bleomycin, etoposide, and cisplatin (JEB) chemotherapy regimens were effective in clinical patients and were effective in the OYST PDX model; therefore, the effect of PDX intervention was consistent with clinical outcomes of OYSTs. CONCLUSION: We have successfully established an OYST PDX model. This OYST model preserves the basic molecular features of the primary human tumor, thereby providing a valuable method to preclinically evaluate new treatments and explore disease pathogenesis.

Collagenated Porcine Heterologous Bone Grafts: Histomorphometric Evaluation of Bone Formation Using Different Physical Forms in a Rabbit Cancellous Bone Model.

Collagenated porcine-derived bone graft materials exhibit osteoconductive properties and the development of different formulations intends to enhance bone regeneration. This study aims to evaluate bone healing in a rabbit cancellous bone defect in response to grafting with different physicochemical forms of heterologous porcine bone. Twenty-six adult male New Zealand White rabbits received two critical size femoral bone defects per animal (n = 52), each randomly assigned to one of the five tested materials (Apatos, Gen-Os, mp3, Putty, and Gel 40). Animals were sacrificed at 15- and 30-days post-surgery. Qualitative and quantitative (new bone, particle and connective tissue percentages) histological analyses were performed. Histomorphometry showed statistically significant differences in all evaluated parameters between mp3 and both Putty and Gel 40 groups, regardless of the timepoint (p < 0.05). Moreover, statistical differences were observed between Apatos and both Putty (p = 0.014) and Gel 40 (p = 0.007) groups, at 30 days, in regard to particle percentage. Within each group, regarding new bone formation, mp3 showed significant differences (p = 0.028) between 15 (40.93 ± 3.49%) and 30 (52.49 ± 11.04%) days. Additionally, intragroup analysis concerning the percentage of particles revealed a significant reduction in particle occupied area from 15 to 30 days in mp3 and Gen-Os groups (p = 0.009). All mp3, Gen-Os and Apatos exhibited promising results in terms of new bone formation, thus presenting suitable alternatives to be used in bone regeneration.

Using the Microwell-mesh to culture microtissues in vitro and as a carrier to implant microtissues in vivo into mice.

Prostate cancer (PCa) patient-derived xenografts (PDXs) are commonly propagated by serial transplantation of "pieces" of tumour in mice, but the cellular composition of pieces is not standardised. Herein, we optimised a microwell platform, the Microwell-mesh, to aggregate precise numbers of cells into arrays of microtissues, and then implanted the Microwell-mesh into NOD-scid IL2γ-/- (NSG) mice to study microtissue growth. First, mesh pore size was optimised using microtissues assembled from bone marrow-derived stromal cells, with mesh opening dimensions of 100×100 µm achieving superior microtissue vascularisation relative to mesh with 36×36 µm mesh openings. The optimised Microwell-mesh was used to assemble and implant PCa cell microtissue arrays (hereafter microtissues formed from cancer cells are referred to as microtumours) into mice. PCa cells were enriched from three different PDX lines, LuCaP35, LuCaP141, and BM18. 3D microtumours showed greater in vitro viability than 2D cultures, but neither proliferated. Microtumours were successfully established in mice 81% (57 of 70), 67% (4 of 6), 76% (19 of 25) for LuCaP35, LuCaP141, and BM18 PCa cells, respectively. Microtumour growth was tracked using live animal imaging for size or bioluminescence signal. If augmented with further imaging advances and cell bar coding, this microtumour model could enable greater resolution of PCa PDX drug response, and lead to the more efficient use of animals. The concept of microtissue assembly in the Microwell-mesh, and implantation in vivo may also have utility in implantation of islets, hair follicles or other organ-specific cells that self-assemble into 3D structures, providing an important bridge between in vitro assembly of mini-organs and in vivo implantation.

Surgical Transplantation of Human RPE Stem Cell-Derived RPE Monolayers into Non-Human Primates with Immunosuppression.

Recent trials of retinal pigment epithelium (RPE) transplantation for the treatment of disorders such as age-related macular degeneration have been promising. However, limitations of existing strategies include the uncertain survival of RPE cells delivered by cell suspension and the inherent risk of uncontrolled cell proliferation in the vitreous cavity. Human RPE stem cell-derived RPE (hRPESC-RPE) transplantation can rescue vision in a rat model of retinal dystrophy and survive in the rabbit retina for at least 1 month. The present study placed hRPESC-RPE monolayers under the macula of a non-human primate model for 3 months. The transplant was able to recover in vivo and maintained healthy photoreceptors. Importantly, there was no evidence that subretinally transplanted monolayers underwent an epithelial-mesenchymal transition. Neither gliosis in adjacent retina nor epiretinal membranes were observed. These findings suggest that hRPESC-RPE monolayers are safe and may be a useful source for RPE cell replacement therapy.

Community Hospital Experience With Bovine Tissue in Infected Vascular Fields.

BACKGROUND: Vascular prosthetic graft infections are rare but associated with high morbidity and mortality. Treatment involves removal of the infected graft requiring arteriotomy closure. Previously this was performed with autologous graft, but bovine tissue has increasingly been used. The objective of this paper is to review the community hospital experience with bovine tissue repair in an infected vascular field. MATERIALS AND METHODS: A retrospective review of all cases performed by a single surgeon in a community hospital for infected prosthetic grafts was completed. Sixteen cases were included where bovine tissue was used for repair. Presentation, location of graft, and causative organism were reviewed, and outcomes including reoperation and mortality were recorded. RESULTS: Of the 16 patients, 15 (94%) had positive cultures of the graft. Methicillin-Resistant Staph Aureus was the most commonly isolated organism (50%). There were 3 unplanned reoperations including a revision from below to above knee amputation, drainage of a hematoma, and a wound debridement within the first year. Over the 1 year follow up period, 3 patients died for a mortality of 19%. There were no reinfections during follow-up. DISCUSSION: Prosthetic graft infection is a rare but serious vascular surgery complication. The causative organism has shifted in the last few years to become increasingly drug resistant. Treatment requires excision, and bovine tissue has been demonstrated to provide a safe and durable method of repair.

Safety of Irradiated Homologous Costal Cartilage Graft in Cleft Rhinoplasty.

BACKGROUND: Autologous cartilage grafts have a low risk of infection and extrusion in cleft rhinoplasty. However, harvesting autologous cartilage involves donor-site morbidity and increased time under anesthesia. Irradiated homologous costal cartilage grafts may be an effective alternative. METHODS: A retrospective study was performed on patients with a history of cleft lip who underwent rhinoplasty for cleft nasal deformity at Johns Hopkins Hospital from 2009 to 2018. Patients were excluded if their rhinoplasty did not involve a cartilage graft. RESULTS: One hundred sixty-five cleft rhinoplasties (patient age, 2 to 72 years; 52 percent female) were performed. Median follow-up time was 256 days; 30 percent were revision operations. Ninety-six procedures (58 percent) used irradiated homologous costal cartilage grafts, with the remaining using autologous cartilage. Complications resulted from 18 procedures (11 percent), seven (10 percent) involving autologous cartilage and 11 (12 percent) involving irradiated homologous costal cartilage. Most autologous cartilage complications (86 percent) required operative intervention, versus seven of 11 (64 percent) for irradiated homologous costal cartilage. Complications associated with irradiated homologous costal cartilage included infection (n = 5), warping (n = 2), and extrusion (n = 1), while two patients with autologous cartilage experienced collapse and one each experienced resorption, warping, and hypertrophic donor-site scarring. There was no difference between groups regarding complication rate or complications requiring operative intervention (p = 0.3 and p = 0.5, respectively). CONCLUSIONS: Irradiated homologous costal cartilage grafts are equally safe and effective as autologous cartilage for use in cleft rhinoplasty. These grafts are readily available and eliminate donor-site morbidity. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

ARG1 functions as a tumor suppressor in breast cancer.

Arginase I (ARG1) is a cytosolic enzyme that catalyzes the hydrolysis of L-arginine to L-ornithine and urea. The association of ARG1 with cancer has mostly been focused on the ARG1 released by tumor-associated myeloid cells in tumor microenvironment. However, the role of ARG1 expressed in cancer cells is unclear. Here, we showed that the expression of ARG1 in human breast cancer (BC) is related to a good prognosis in BC patients. Overexpression of ARG1 suppresses BC cell proliferation and migration in vitro and xenograft tumor growth and development in mouse models. Furthermore, ARG1 expression down-regulates the expression of p-AKT, leading to the de-activation of AKT signal pathway in BC cells. Thus, our results established that in contrast to the role of ARG1 released from tumor-associated myeloid cells in tumor microenvironment that promotes tumor immune escape, ARG1 expressed in BC cells suppresses AKT signaling pathway and functions as a tumor suppressor.

Simultaneous Perio-endo Surgery with ER:YAG Laser and Bone Xenograft. A Case Report.

Periodontally affected teeth with periapical lesion indicated for periapical surgery have a poor prognosis. Using Er:YAG lasers to perform simultaneous surgery on both defects may increase their survival rate. Preparing a retrograde cavity on affected teeth and obturating it is still a matter of debate among clinicians. The purpose of this case report was to describe the simultaneous use of Erbium-doped Yttrium Aluminium Garnet Er:YAG (2,940 nm) laser in the treatment of periapical granuloma and infraossal defect and the achieved results. The Er:YAG laser was used to perform flap dissection, granulation tissue removal, osteotomy and root-end resection except for initial flap incision and reflection. The cystic cavity was filled with Bio-Oss Collagen® xenograft. Results were followed up for 18 months with the help of radiographic orthopantomographic images. The outcome of this clinical case indicates that the use of Er:YAG laser could be considered a suitable method to perform simultaneous periodontal and endodontic surgery.

Generation of foxn1/Casper Mutant Zebrafish for Allograft and Xenograft of Normal and Malignant Cells.

Cell transplantation into immunodeficient recipients is a widely used approach to study stem cell and cancer biology; however, studying cell states post transplantation in vivo is inconvenient in mammals. Here, we generated a foxn1/Casper mutant zebrafish that is transparent and exhibits T cell deficiency. By employing the line for hematopoietic stem cell (HSC) transplantation (HSCT), we could achieve nonconditioned transplantation. Meanwhile, we found that fetal HSCs from 3 days post fertilization zebrafish embryos produce a better transplant outcome in foxn1/Casper mutants, compared with adult HSCs. In addition to HSCT, the foxn1/Casper mutant is feasible for allografts of myelodysplastic syndrome-like and muscle cells, as well as xenografts of medaka muscle cells. In summary, foxn1/Casper mutants permit the nonconditioned engraftment of multiple cell types and visualized characterization of transplanted cells in vivo.

Investigating the Osteoinductive Potential of a Decellularized Xenograft Bone Substitute.

Bone grafting is the second most common tissue transplantation procedure worldwide. One of the alternative methods for bone repair under investigation is a tissue-engineered bone substitute. An ideal property of tissue-engineered bone substitutes is osteoinductivity, defined as the ability to stimulate primitive cells to differentiate into a bone-forming lineage. In the current study, we use a decellularization and oxidation protocol to produce a porcine bone scaffold and examine whether it possesses osteoinductive potential and can be used to create a tissue-engineered bone microenvironment. The decellularization protocol was patented by our lab and consists of chemical decellularization and oxidation steps using combinations of deionized water, trypsin, antimicrobials, peracetic acid, and triton-X100. To test if the bone scaffold was a viable host, preosteoblasts were seeded and analyzed for markers of osteogenic differentiation. The osteoinductive potential was observed in vitro with similar osteogenic markers being expressed in preosteoblasts seeded on the scaffolds and demineralized bone matrix. To assess these properties in vivo, scaffolds with and without preosteoblasts preseeded were subcutaneously implanted in mice for 4 weeks. MicroCT scanning revealed 1.6-fold increased bone volume to total volume ratio and 1.4-fold increase in trabecular thickness in scaffolds after implantation. The histological analysis demonstrates new bone formation and blood vessel formation with pentachrome staining demonstrating osteogenesis and angiogenesis, respectively, within the scaffold. Furthermore, CD31+ staining confirmed the endothelial lining of the blood vessels. These results demonstrate that porcine bone maintains its osteoinductive properties after the application of a patented decellularization and oxidation protocol developed in our laboratory. Future work must be performed to definitively prove osteogenesis of human mesenchymal stem cells, biocompatibility in large animal models, and osteoinduction/osseointegration in a relevant clinical model in vivo. The ability to create a functional bone microenvironment using decellularized xenografts will impact regenerative medicine, orthopedic reconstruction, and could be used in the research of multiple diseases.

Insulin-producing organoids engineered from islet and amniotic epithelial cells to treat diabetes.

Maintaining long-term euglycemia after intraportal islet transplantation is hampered by the considerable islet loss in the peri-transplant period attributed to inflammation, ischemia and poor angiogenesis. Here, we show that viable and functional islet organoids can be successfully generated from dissociated islet cells (ICs) and human amniotic epithelial cells (hAECs). Incorporation of hAECs into islet organoids markedly enhances engraftment, viability and graft function in a mouse type 1 diabetes model. Our results demonstrate that the integration of hAECs into islet cell organoids has great potential in the development of cell-based therapies for type 1 diabetes. Engineering of functional mini-organs using this strategy will allow the exploration of more favorable implantation sites, and can be expanded to unlimited (stem-cell-derived or xenogeneic) sources of insulin-producing cells.

Inhibitory effect of TGF-ß gene modified human amniotic mesenchymal stem cells on rejection after xenotransplantation of peripheral nerves.

OBJECTIVE: To explore the inhibitory effect of transforming growth factor-beta (TGF-ß) gene modified human amniotic mesenchymal stem cells on rejection after xenotransplantation of peripheral nerves. MATERIALS AND METHODS: In this study, 6 placentas collected in our hospital were selected as the source of human amniotic mesenchymal stem cells. A total of 60 C57BL/6 experimental mice (mouse sciatic nerves were removed before the experiment) were taken as research objects. Mice were randomly divided into experimental group 1, experimental group 2 and experimental group 3 (xenogenous peripheral nerves were introduced to all experimental groups), and a control group (autologous peripheral nerves were introduced). Among them, TGF-ß gene modified (overexpression) human amniotic mesenchymal stem cells were introduced to experimental group 1; TGF-ß gene modified (inhibition) human amniotic mesenchymal stem cells were introduced to experimental group 2; normal human amniotic mesenchymal stem cells were introduced to experimental group 3; and autologous sciatic nerves were introduced to control group. The messenger ribonucleic acid (mRNA) and protein expressions of the TGF-ß in different human amniotic mesenchymal stem cells were detected by quantitative polymerase chain reaction (qPCR) and Western blotting, respectively. Mouse sciatic nerve function in each group after 2 weeks of procedures was detected via the CatWalk system. Expression level of interleukin-22 (IL-22) in the peripheral tissues of transplanted nerves and blood was detected using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA). Its mRNA level was examined via fluorescence quantitative PCR. RESULTS: TGF-ß1 was highly expressed in mice of experimental group 1, but lowly expressed in experimental group 2 relative to that of experimental group 3 (p<0.05). CatWalk test results revealed that the main indexes in experimental group 1 were superior to those in other groups, while the main indexes in experimental group 2 were inferior to those in other groups. According to immunohistochemistry and ELISA results, there were significant differences in the expression level of IL-22 in mice of different treatment groups (p<0.05). IL-22 level was the lowest in control group [(5.05±0.15) pg/mL], followed by that in experimental group 1 [(6.52±0.24) pg/mL], and it was the highest in experimental group 2 [(9.47±0.31) pg/mL]. CONCLUSIONS: Human amniotic mesenchymal stem cells overexpressing TGF-ß can inhibit rejection after xenotransplantation of peripheral nerves.

Altered hormonal milieu and dysregulated protein expression can cause spermatogenic arrest in ectopic xenografted immature rat testis.

Testis tissue xenografting complemented with cryopreservation is a feasible technique for fertility preservation in children with malignancy receiving gonadotoxic therapy and for endangered species with high neonatal mortality rate. However, xenografted testis of human and most endangered species are known to undergo spermatogenic arrest. In this study, we xenografted immature rat testis onto immunodeficient male mice to investigate the plausible underlying causes of spermatogenic arrest. Histological analysis of xenografted testes collected 8-wk post-grafting showed incomplete spermatogenesis with pachytene-stage spermatocytes as the most advanced germ cells. Although the levels of serum luteinizing hormone and testosterone were normal in recipient mice, those of follicle stimulating hormone (FSH) were significantly high, and specific receptors of FSH were absent in the xenografts. The xenografts demonstrated dysregulated expression of Sertoli cell-transcriptional regulators (WT1 and SOX9) and secretory proteins (SCF and GDNF). In conclusion, results from our study suggested that an altered hormonal milieu in recipients and dysregulated protein expression in xenografts could be a potential cause of spermatogenic arrest in xenografted immature rat testis. Further stereological analysis of xenografts can demonstrate precise cellular composition of xenografts to decipher interactions between germ and somatic cells to better understand spermatogenic arrest in xenografted testis.

Prospective Clinical and Histologic Evaluation of Alveolar Socket Healing Following Ridge Preservation Using a Combination of Hydroxyapatite and Collagen Biomimetic Xenograft Versus Demineralized Bovine Bone.

PURPOSE: This prospective study is aimed at investigating clinically and histologically the effectiveness of a biomimetic magnesium-enriched-hydroxyapatite (MgHA)/collagen-based bone substitute for alveolar socket preservation. MATERIALS: Patients scheduled for posterior single tooth extraction were included. The alveolar socket was filled either with MgHA or deproteinized bovine bone matrix (DBBM). In DBBM group, a punch of mucosa was taken from the palate and used to cover the graft. Vertical and horizontal dimensional changes of the alveolar process were assessed clinically with a periodontal probe and with 3-dimensional (3D) analysis of a cast model. Postoperative quality of life was assessed through a questionnaire. After 6 months of healing, an alveolar tissue biopsy was taken for histologic and histomorphometric analysis of the newly formed tissue. After checking normality of the distributions, parametric or nonparametric tests were used for statistical comparisons. RESULTS: Twenty patients (12 males, 8 females, mean age 42.8 ±â€Š5.1 years, range 33-50 years) were treated. After 6 months, vertical and horizontal alveolar ridge resorption was similar in the 2 groups. The 3D analysis of the models showed a significantly higher resorption at the buccal side than at the palatal/lingual side. Histomorphometric analysis showed similar new bone formation for MgHA group (23.07 ±â€Š10.3%) and DBBM (22.77 ±â€Š6.95%), and a significantly higher residual material% for DBBM (15.77 ±â€Š1.95%) than MgHA (5.01 ±â€Š1.04%). Significantly less pain was reported in the first 3 days after surgery in patients of the MgHA group. CONCLUSION: The MgHA was as safe and effective as DBBM and may represent a feasible bone substitute for alveolar socket preservation.