Neural tissue tolerance to synthetic dural mater graft implantation in a rabbit durotomy model.

In neurosurgical interventions, effective closure of the dura mater is essential to prevent cerebrospinal fluid leakage and minimize post-operative complications. Biodegradable synthetic materials have the potential to be used as dura mater grafts owing to their regenerative properties and low immunogenicity. This study evaluated the safety of ArtiFascia, a synthetic dura mater graft composed of poly(l-lactic-co-caprolactone acid) and poly(d-lactic-co-caprolactone acid), in a rabbit durotomy model. Previously, ArtiFascia demonstrated positive local tolerance and biodegradability in a 12-month preclinical trial. Here, specialized stains were used to evaluate potential brain damage associated with ArtiFascia use. Histochemical and immunohistochemical assessments included Luxol Fast Blue, cresyl Violet, Masson's Trichrome, neuronal nuclei,, Glial Fibrillary Acidic Protein, and ionized calcium-binding adaptor molecule 1 stains. The stained slides were graded based on the brain-specific reactions. The results showed no damage to the underlying brain tissue for either the ArtiFascia or control implants. Neither inflammation nor neuronal loss was evident, corroborating the safety of the ArtiFascia. This approach, combined with previous histopathological analyses, strengthens the safety profile of ArtiFascia and sets a benchmark for biodegradable material assessment in dura graft applications. This study aligns with the Food and Drug Administration guidelines and offers a comprehensive evaluation of the potential neural tissue effects of synthetic dura mater grafts.

Assessment of Bioprotect's Biodegradable Balloon System as a Rectal Spacer in Radiotherapy: An Animal Study on Tissue Response and Biocompatibility.

Prostate cancer is a significant health concern for men, emphasizing the need for effective treatment strategies. Dose-escalated external beam radiotherapy shows promise in improving outcomes but presents challenges due to radiation effects on nearby structures, such as the rectum. Innovative techniques, including rectal spacers, have emerged to mitigate these effects. This study comprehensively assessed tissue responses following the implantation of the Bioprotect biodegradable fillable balloon as a rectal spacer in a rat model. Evaluation occurred at multiple time points (4, 26, and 52 weeks) post-implantation. Results revealed localized tissue responses consistent with the expected reaction to biodegradable materials, characterized by mild to moderate fibrotic reactions and encapsulation, underscoring the safety and biocompatibility of the balloon. Importantly, no other adverse events occurred, and the animals remained healthy throughout the study. These findings support its potential clinical utility in radiotherapy treatments to enhance patient outcomes and minimize long-term implant-related complications, serving as a benchmark for future similar studies and offering valuable insights for researchers in the field. In conclusion, the findings from this study highlight the safety, biocompatibility, and potential clinical applicability of the Bioprotect biodegradable fillable balloon as a promising rectal spacer in mitigating radiation-induced complications during prostate cancer radiotherapy.

Preclinical In Vivo Safety of Poly-Phosphorylated Superlubrication Vectors for the Treatment of Osteoarthritis.

Osteoarthritis (OA) can lead to a significant functional disability. Poly[2-(methacryloyloxy)ethyl phosphorylcholine] (pMPC) liposomes are a novel treatment modality for OA, intended to restore the natural lubrication properties of articular cartilage. Here, we report on two studies aimed to assess the local and systemic safety and toxicity of pMPCylated liposomes in comparison with physiological saline, in Sprague-Dawley (SD) rats and in sheep after a single intra-articular (IA) injection. The animals were sacrificed after 1 and 6 weeks (rats) and 3 and 6 weeks (sheep). No signs of toxicity or abnormal clinical findings were observed. Histopathological evaluation revealed no signs of reactivity or abnormal findings in the injected joints or in any other organs. In conclusion, a single IA injection of the pMPCylated liposomes demonstrated an excellent safety profile and did not result in local reactivity or systemic toxicity, thus supporting its further development for use in humans.

rVSV-ΔG-SARS-CoV-2-S vaccine: repeated intramuscular (IM) toxicity, local tolerance, immunogenicity and biodistribution study in NZW rabbits.

BriLife®, a vector-based vaccine that utilizes the recombinant vesicular stomatitis virus (VSV) platform to express and present the spike antigen of SARS-CoV-2, is undergoing testing in a phase 2 clinical trial in Israel. A nonclinical repeated-dose (GLP) toxicity study in New Zealand white rabbits was performed to evaluate the potential toxicity, local tolerance, immunogenicity and biodistribution of the vaccine. rVSV-ΔG-SARS-CoV-2-S (or vehicle) was administered intramuscularly to two groups of animals (106, 107 PFU/animal, n = 10/sex/group) on three occasions, at 2-week intervals, followed by a 3-week recovery period. Systemic clinical signs, local reactions, body weight, body temperature, food consumption, ophthalmology, urinalysis, clinical pathology, C-reactive protein, viremia and antibody levels were monitored. Gross pathology was performed, followed by organs/tissues collection for biodistribution and histopathological evaluation. Treatment-related changes were restricted to multifocal minimal myofiber necrosis at the injection sites, and increased lymphocytic cellularity in the iliac and mesenteric lymph nodes and in the spleen. These changes were considered related to the inflammatory reaction elicited, and correlated with a trend for recovery. Detection of rVSV-ΔG-SARS-CoV-2-S vaccine RNA was noted in the regional iliac lymph node in animals assigned to the high-dose group, at both termination time points. A significant increase in binding and neutralizing antibody titers was observed following vaccination at both vaccine doses. In view of the findings, it was concluded that the rVSV-ΔG-SARS-CoV-2-S vaccine is safe. These results supported the initiation of clinical trials.

Preliminary nonclinical safety and immunogenicity of an rVSV-ΔG-SARS-CoV-2-S vaccine in mice, hamsters, rabbits and pigs.

rVSV-ΔG-SARS-CoV-2-S is a clinical stage (Phase 2) replication competent recombinant vaccine against SARS-CoV-2. To evaluate the safety profile of the vaccine, a series of non-clinical safety, immunogenicity and efficacy studies were conducted in four animal species, using multiple doses (up to 108 Plaque Forming Units/animal) and dosing regimens. There were no treatment-related mortalities or any noticeable clinical signs in any of the studies. Compared to unvaccinated controls, hematology and biochemistry parameters were unremarkable and no adverse histopathological findings. There was no detectable viral shedding in urine, nor viral RNA detected in whole blood or serum samples seven days post vaccination. The rVSV-ΔG-SARS-CoV-2-S vaccination gave rise to neutralizing antibodies, cellular immune responses, and increased lymphocytic cellularity in the spleen germinal centers and regional lymph nodes. No evidence for neurovirulence was found in C57BL/6 immune competent mice or in highly sensitive type I interferon knock-out mice. Vaccine virus replication and distribution in K18-human Angiotensin-converting enzyme 2-transgenic mice showed a gradual clearance from the vaccination site with no vaccine virus recovered from the lungs. The nonclinical data suggest that the rVSV-ΔG-SARS-CoV-2-S vaccine is safe and immunogenic. These results supported the initiation of clinical trials, currently in Phase 2.

Safety and Performance Evaluation of Su2ura Approximation, a New Suturing Device, in Pigs.

One of the challenging aspects of minimal invasive surgery (MIS) is intracorporal suturing, which can be significantly time-consuming. Therefore, there is a rising need for devices that can facilitate the suturing procedure in MIS. Su2ura Approximation Device (Su2ura Approximation) is a novel device developed to utilize the insertion of anchors threaded with stitches to allow a single action placement of a suture. The objective of this study was to evaluate the long-term safety and tissue approximation of Su2ura Approximation in comparison to Endo Stitch + Surgidac sutures in female domestic pigs. All incision sites were successfully closed by both methods. Firm consolidation within and around the incision site was noted in several animals in both treatment groups, which corresponded histopathologically to islands of ectopic cartilage or bone spicules within the fibrotic scar. These changes reflect heterotopic ossification that is commonly seen in the healing of abdominal operation sites in pigs. No other abnormal findings were observed throughout the study period. In conclusion, the use of Su2ura Approximation under the present experimental conditions revealed no safety concerns.

Safety and efficacy of sFilm-FS, a novel biodegradable fibrin sealant, in Göttingen minipigs.

Bleeding during surgical procedures is a common complication. Therefore, hemostatic agents have been developed to control bleeding, and fibrin sealants have several benefits. sFilm-FS is a novel fibrin sealant that comprises a biodegradable co-polymeric film embedded with human fibrinogen and thrombin. Herein, the safety and efficacy of sFilm-FS were compared using a liver and spleen puncture model of Göttingen minipigs with those of the standard hemostatic techniques (control animals) and EVARREST®, a reference fibrin sealant. Hemostasis and reduced blood loss were more effectively achieved with sFilm-FS than with the standard techniques in the control animals and comparable to those achieved with EVARREST®. No treatment-related adverse effects were observed in any of the groups. Histopathological evaluation indicated that sFilm-FS was slightly and moderately reactive at the liver puncture site and spleen, respectively, compared with the standard techniques in the control animals. These changes are expected degradation reactions of the co-polymeric film and are not considered as adverse events. No treatment-related abnormalities were noted in the other evaluated organs. Additionally, no evidence of local or systemic thromboses was noted. These results support the use of sFilm-FS for hemostasis in humans.

Treatment of contaminated radial fracture in Sprague-Dawley rats by application of a degradable polymer releasing gentamicin.

Fracture-related infections remain a leading cause of morbidity and mortality. We aimed to establish a simple contaminated radial osteotomy model to assess the efficacy of a biodegradable polymer poly(sebacic-co-ricinoleic acid) [p(SA-RA)] containing 20% w/w gentamicin. A unilateral transverse osteotomy was induced in Sprague-Dawley (SD) rats, followed by application of Staphylococcus aureus suspension over the fracture. After successfully establishing the contaminated open fracture model, we treated the rats either systemically (intraperitoneal cefuroxime), locally with p(SA-RA) containing gentamicin, or both. Control groups included non-contaminated group and contaminated groups that were either untreated or treated with the polymer alone. After 4 weeks, the bones were subjected to micro-CT scanning and microbiological and histopathology evaluations. Micro-CT analysis revealed similar changes in the group subjected to both local and systemic treatment as in the non-contaminated control group. Lack of detectable bacterial growth was noted in most animals of the group subjected to both local and systemic treatment, and all samples were negative for S. aureus. Histopathological evaluation revealed that all treatment modalities containing antibiotics were highly effective in reducing infection and promoting callus repair, resulting in early bone healing. While p(SA-RA) containing gentamicin treatment showed better results than cefuroxime, the combination of local and systemic treatment displayed the highest therapeutic potential in this model.

Local Tolerance and Biodegradability of a Novel Artificial Dura Mater Graft Following Implantation Onto a Dural Defect in Rabbits.

Dura mater defects are a common problem following neurosurgery. Dural grafts are used to repair these defects; among them are biodegradable polymeric synthetic grafts. ArtiFascia is a novel synthetic and fibrous Dural graft, composed of poly(l-lactic-co-caprolactone acid) (PLCL) and poly(d-lactic-co-caprolactone acid). In this study, the biodegradability and local tolerance of ArtiFascia was evaluated in rabbits and compared with a bovine collagen matrix as a reference control. ArtiFascia implantation resulted in the formation of neo-dura at the site of implantation and recovery of the dural damage and the calvaria bone above. The implanted graft was completely absorbed after 12 months and the remaining macrophages were morphologically consistent with the anti-inflammatory M2-like phenotype, which contributes to tissue healing and are not pro-inflammatory. The site of the drilled skull bone had a continuous smooth surface, without exuberant tissue or inflammation and a newly formed trabecular bone formation indicated the healing process of the bone. These results support the local tolerability and biodegradability of ArtiFascia when used as a dural graft in rabbits. This study suggests that PLCL-based grafts including ArtiFascia are safe and effective to repair Rabbit Dura.

Local Tolerability and Performance Evaluation in Domestic Pigs of a Fractional Radiofrequency Device for Dermatologic Treatment.

Information on the safety of energy-based dermatological surgical devices in domestic pigs, and fractional radiofrequency (RF) devices in particular, is very limited. The aim of this study was to evaluate in a GLP-compliant study in domestic pigs the local reaction and performance of a novel fractional RF device. Five female domestic pigs were subjected to fractional RF pulses, using different energy and pulse durations and depth of penetration of the pulses. The animals were evaluated clinically and histologically at different time points (days 0, 1, 3, 7, and 14) postenergy exposure. There were no microscopic or macroscopic local adverse effects in any tested power settings, and there was time-related progressive healing, reaching complete macroscopic and microscopic healing by 7 days postapplication. As expected, there was power-related progressive increase in the incidence of ablation (destruction of skin tissue by vaporization) and coagulative necrosis of the dermis from low to high power setting. This comprehensive study, using multiple power settings (both ablative and coagulative) and several time points, will be of benefit for future studies evaluating new fractional RF devices.

Biodegradability and Safety Study of LifeMesh™, a Novel Self-adhesive Mesh, in Sprague-Dawley Rats.

Self-adhesive meshes are being developed to avoid complications due to traumatic fixation methods. LifeMesh™ is a novel self-adhesive mesh with a biodegradable gelatin adhesive layer developed for hernia repair. The aim of this study was to assess the safety and biodegradability of LifeMesh in Sprague-Dawley (SD) rats for 6 weeks, in comparison to a bare polypropylene (BPP) mesh fixed with sutures. LifeMesh was tolerated well and its implantation did not result in any adverse local reaction, and its adhesive layer was substantially degraded after 4 weeks. Histopathological examination revealed that the presence of the adhesive contributed to a uniform thickness of the granulation tissue surrounding the mesh, in contrast to a nonuniform granulation tissue with BPP. Nonuniform granulation tissue suggests that there will be poorer integration of the mesh to the abdominal wall. The use of LifeMesh also resulted in less adhesions of internal organs with a smaller surface area of involvement. These findings lend support to the potential benefit of LifeMesh for hernia repair in humans and expand the available information on the typical histopathological findings expected with biodegradable implants in the peritoneal cavity of SD rats.

Compact MRI for the detection of teratoma development following intrathecal human embryonic stem cell injection in NOD-SCID mice.

Stem cells are emerging as a promising new treatment modality for a variety of central nervous system disorders. However, their use is hampered by the potential for the development of teratomas and other tumors. Therefore, there is a crucial need for the development of methods for detecting teratomas in preclinical safety studies. The aim of the current study is to assess the ability of a compact Magnetic Resonance Imaging (MRI) system to detect teratoma formation in mice. Five NOD-SCID mice were injected intrathecally with human embryonic stem cells (hESCs), with two mice serving as controls. In vivo MRI was performed on days 25 and 48, and ex vivo MRI was performed after scheduled euthanization (day 55). MRI results were compared to histopathology findings. Two animals injected with hESCs developed hind-limb paresis and paralysis, necessitating premature euthanization. MRI examination revealed abnormal pale areas in the spinal cord and brain, which correlated histopathologically with teratomas. This preliminary study shows the efficacy of compact MRI systems in the detection of small teratomas following intrathecal injection of hESCs in a highly sensitive manner. Although these results should be validated in larger studies, they provide further evidence that the use of MRI in longitudinal studies offers a new monitoring strategy for preclinical testing of stem cell applications.

Pulmonary thrombosis in the mouse following intravenous administration of quantum dot-labeled mesenchymal cells.

Quantum dots (QDs) are emerging as novel diagnostic agents. Yet, only a few studies have examined the possible deleterious effects of QD-labeled stem cells. We assessed the potential toxic effects of QD-labeled human embryonic palatal mesenchymal (QD-HEPM) cells in male NOD/SCID mice for six months, following the administration of a single intravenous injection. Control animals were administered with non-labeled HEPM cells. No treatment-related clinical signs, hematological, or biochemical parameters were found in the QD-HEPM animals in comparison to control animals. Histologically, multifocal organizing thrombi were noted in the pulmonary arteries of all QD-HEPM animals from the one-week study group and in one animal from the one-month group. Additionally, increased severity of perivascular inflammation was noted at the injection sites of QD-HEPM animals from the one-week group. This is the first study reporting histopathological evidence for pro-thrombotic adverse effects mediated by QD labeling.

Safety and biodistribution profile of placental-derived mesenchymal stromal cells (PLX-PAD) following intramuscular delivery.

The administration of mesenchymal stromal cells (MSCs) provides an exciting emerging therapeutic modality for the treatment of peripheral arterial disease, a condition that is associated with critical limb ischemia as its end stage. Placental-derived MSCs, termed PLX-PAD cells, are stable adhesive stromal cells isolated from full-term human placentae, cultured on carriers, and expanded in a bioreactor called the PluriX. These cells can be expanded in vitro without phenotypic or karyotypic changes. We studied the safety and biodistribution properties of PLX-PAD cells following intramuscular administration in NOD/SCID mice. No significant clinical signs, hematological and biochemical parameters, or major pathological changes were found in PLX-PAD-treated animals in comparison to vehicle controls. Several animals in the control and PLX-PAD-treated groups developed thymic malignant lymphoma, first seen after one month, as expected in this mouse strain. In addition, both groups developed spontaneous mesenteric vessel inflammation. Real-time quantitative polymerase chain reaction (RT-qPCR) demonstrated that distribution of PLX-PAD cells was confined to the injection site. Placental-derived MSCs remained in this site with gradual decrease in concentration during a three-month period. In view of these data, we conclude that the administration of PLX-PAD cells is not associated with any adverse effects in NOD/SCID mice.