BACKGROUND: Spermatogonial Stem Cells (SSCs) are the only stem cells in adults that can transfer genetic information to future generations. Considering that a single SSC gives rise to a vast number of spermatozoa, genetic manipulation of these cells is a potential novel technology with practical application to various animal species. OBJECTIVES: The aim of this study was to evaluate Enhanced Green Fluorescent Protein (EGFP) gene transfection into bovine spermatogonial colonies via liposome carrier and assess the best incubation day in uptake exogenous gene by spermatogonial colonies. METHODS: Transfection efficiency EGFP gene through lipofection was determined different in three days (day 4, 6 and 8) after the beginning of the culture by fluorescent microscope. Immunofluorescent staining against OCT4 and vimentin led to the confirmation of the nature of both SSCs and sertoli cells. RESULTS: Results showed that the transfected colonies through lipofection increased significantly (p<0.05) in each three days of transfection in comparison with those of the control groups. The transfection colonies were higher (significant) in comparision with those of the free exogenous gene carrier groups. The rate of infected colonies was higher when transfection proceed day 4. CONCLUSIONS: It was concluded that lipofectamine can be used safely for direct loading of exogenous DNA to spermatogonila colony, particularly during the fourth day of culture.

OBJECTIVE To evaluate gene transfer of recombinant adeno-associated viral (rAAV) vectors with AAV2 or AAV5 capsid and encoding hyaluronic acid (HA) synthase-2 (HAS2) into joints of healthy dogs. ANIMALS 22 purpose-bred Beagles. PROCEDURES Plasmid expression cassettes encoding canine HAS2 (cHAS2) were assessed in vitro for concentration and molecular size of secreted HA. Thereafter, rAAV2-cHAS2 vectors at 3 concentrations and rAAV5-cHAS2 vectors at 1 concentration were each administered intra-articularly into the left stifle joint of 5 dogs; 2 dogs received PBS solution instead. Synovial fluid HA concentration and serum and synovial fluid titers of neutralizing antibodies against AAV capsids were measured at various points. Dogs were euthanized 28 days after treatment, and cartilage and synovium samples were collected for vector DNA and mRNA quantification and histologic examination. RESULTS Cell transfection with plasmids encoding cHAS2 resulted in an increase in production and secretion of HA in vitro. In vivo, the rAAV5-cHAS2 vector yielded uniform genome transfer and cHAS2 expression in collected synovium and cartilage samples. In contrast, rAAV2-cHAS2 vectors were detected inconsistently in synovium and cartilage samples and failed to produce clear dose-related responses. Histologic examination revealed minimal synovial inflammation in joints injected with rAAV vectors. Neutralizing antibodies against AAV capsids were detected in serum and synovial fluid samples from all vector-treated dogs. CONCLUSIONS AND CLINICAL RELEVANCE rAAV5-mediated transfer of the gene for cHAS2 into healthy joints of dogs by intra-articular injection appeared safe and resulted in vector-derived cHAS2 production by synoviocytes and chondrocytes. Whether this treatment may increase HA production by synoviocytes and chondrocytes in osteoarthritic joints remains to be determined.

Objective: To evaluate agents used for delivery of small interfering RNAs (siRNAs) into feline corneal cells, toxicity of the delivery agents, and functionality of anti-feline herpesvirus 1 (FHV-1)–specific siRNA combinations. Sample: Feline primary corneal cells and 19 six-month-old colony-bred cats. Procedures: siRNA delivery into corneal cells via various delivery agents was evaluated via flow cytometric detection of labeled siRNAs. Cellular toxicity was evaluated with a proliferation assay. Functionality was tested via quantitative reverse transcriptase PCR assay, plaque assay, and flow cytometry. In vivo safety was evaluated with an ocular scoring method following topical application of delivery agents containing siRNAs into eyes. Corneal biopsy specimens were used to assess safety and uptake of siRNAs into corneal cells. Results: Use of 3 delivery agents resulted in > 95% transfection of primary corneal cells. Use of a peptide for ocular delivery yielded approximately 82% transfection of cells in vitro. In cultured corneal cells, use of the siRNA combinations resulted in approximately 76% to 89% reduction in FHV-1–specific mRNA, 63% to 67% reduction of FHV-1–specific proteins in treated cells, and 97% to 98% reduction in FHV-1 replication. The agents were nonirritating in eyes, caused no substantial clinical ocular signs, and were nontoxic. Histologically, corneal epithelium and stroma were normal in treated cats. However, none of the agents were effective in delivering siRNAs into the corneal cells in vivo. Conclusions and Clinical Relevance: The tested anti–FHV-1–specific siRNAs could potentially be used as a treatment for FHV-1 if a successful means of in vivo delivery can be achieved.

Bone repair in horses implies invasive surgeries and increased cost. Research on musculoskeletal disorders therapy in horses includes cell-based therapy with mesenchymal stromal cells (MSCs). Mesenchymal stromal cells can be obtained from bone marrow (BMMSCs). Unfortunately, BMMSCs have limited cell replication in vitro. The objective of this study was to develop a biologically immortalized equine stem cell line derived from bone marrow, with unlimited in-vitro proliferation and the ability to differentiate into bone cells. Equine BMMSCs were transfected and immortalized with human telomerase reverse transcriptase (hTERT) gene. Cell passages from equine immortal BMMSCs were characterized by the presence of stemness CD markers and expression of multi-potent differentiation genes (OCT-4, SOX2, and NANOG). Equine immortal BMMSCs were incubated in osteogenic medium and bone cell differentiation was determined by alkaline phosphatase and von Kossa staining, and osteogenic gene expression (osteocalcin, Runx2, and osterix). Telomerase activity was determined by telomeric repeat amplification technique. Results showed that equine immortal BMMSCs were able to replicate in-vitro up to passage 50 and maintain stem cell characteristics by the presence of CD90 and expression of multi-potent genes. Equine immortal BMMSCs were able to differentiate into bone cells, which was confirmed by the positive osteogenic staining and gene expression. Equine BMMSCs were successfully immortalized and maintained characteristics of stem cells and readily differentiated into osteogenic cells. Extending the life span of equine BMMSCs by transfection of the hTERT gene will revolutionize the clinical use of MSCs by making them available to orthopedic surgeons "off the shelf."

Objective-To evaluate 2 commercially available transfection reagents for transfection efficiency and distribution of small interfering RNA (siRNA) molecules to chondrocytes in monolayer cultures and full-thickness cartilage explants from guinea pigs and horses. Sample-Cartilage explants from 5 one-month-old and 3 adult guinea pigs and 5 adult clinically normal horses. Procedures-Monolayer chondrocytes and uniform cartilage explants were exposed to 1 of 2 siRNA transfection complexes according to manufacturers' protocols (1micromolar [1×]). Additionally, monolayer chondrocytes were exposed to 2× the suggested amount of a proprietary siRNA molecule. Full-thickness cartilage explants were treated with 1× (1micromolar), 2× (2micromolar), and 4× (4micromolar) or 1× (0.13micromolar), 4× (0.52micromolar), and 8× (1.04micromolar) the recommended concentrations of the proprietary siRNA and the cationic liposome siRNA, respectively, in equivalent media volumes. Use of fluorescent siRNA duplexes allowed quantification of transfected cells via flow cytometry and direct visualization of the depth and distribution of in situ transfection via fluorescent microscopy. Results-With both transfection reagents, > 90% of monolayer chondrocytes were transfected. In explants, only use of the proprietary molecule achieved > 50% transfection efficiency, whereas use of the cationic liposome achieved < 20%. Only the proprietary molecule-treated cartilage consistently contained fluorescent cells throughout all zones; the cationic liposome-transfected chondrocytes were restricted to explant surfaces. Conclusions and Clinical RelevanceRobust transfection of chondrocytes in monolayer was achieved with both reagents, but only use of the proprietary molecule attained effective full-thickness transfection of explants that may allow relevant transcript reduction via RNAi.

Objective-To use transient and stable transfection of Chinese hamster ovary cells to clone the gene encoding feline erythropoietin (feEPO) protein, characterize the expressed protein, and assess its biological activity. Sample Population-Cultures of Chinese hamster ovary or TF-1 cells. Procedure-The gene encoding feEPO was cloned into a eukaryotic expression plasmid. Chinese hamster ovary cells were transiently or stably transfected with the plasmid. Expressed recombinant feEPO (rfeEPO) protein was purified from transiently transfected cells. The protein was characterized by use of SDS gel electrophoresis and western blot analysis. Biological activity was assessed by measuring thymidine incorporation by TF-1 erythroleukemic cells. Results-Purified rfeEPO from supernatants of transiently transfected cells was determined to be 34 to 40 kilodaltons (kd) by use of SDS gel electrophoresis, whereas the molecular weight predicted from the amino acid sequence was 21.5 kd. The banding pattern and high molecular weight suggested the protein was glycosylated. The rfeEPO proteins derived from transient or stable transfections subsequently were determined to be biologically active in vitro. Conclusions and Clinical Relevance-The gene encoding feEPO can be transfected into eukaryotic cells, and the expressed rfeEPO protein is biologically active in vitro. Cats with chronic renal failure often are anemic as a result of reduced expression of erythropoietin (EPO). Treatment with human-derived EPO stimulates RBCs in anemic cats; however, treatment is often limited by the development of antibodies directed against the recombinant human protein, which can then cross-react with endogenous feEPO. Recombinant feEPO may prove beneficial for use in cats with chronic renal failure.