Comparison of Freshly Isolated Adipose Tissue-derived Stromal Vascular Fraction and Bone Marrow Cells in a Posterolateral Lumbar Spinal Fusion Model

Synthesis and Preclinical Evaluation of a Novel Oxy133-Infused Biomimetic Bone Graft Using a Rat Model of Posterolateral Spinal Fusion

OBJECTIVE

To 1) create a novel tissue-engineered bone graft comprising the osteoinductive oxysterol Oxy133 and 2) compare the osteogenic capability of this novel bone graft with bone graft substitutes previously examined.

METHODS

Oxy133 was homogeneously incorporated into a biomimetic (BioMim) bone graft substitute comprising extracellular matrix and calcium phosphates. Two iterations of the graft were created: one corresponding to an implant-dose of 2.0 mg Oxy133 (BioMim-Oxy133-Lo) and the other corresponding to an implant-dose of 20 mg Oxy133 (BioMim-Oxy133-Hi). Thirty-two male Sprague-Dawley rats were allocated randomly to 4 equally sized groups: 1) BioMim-Oxy133-Lo, 2) BioMim-Oxy133-Hi, 3) absorbable collagen sponge (ACS) with topically applied Oxy133 dissolved in dimethyl sulfoxide (ACS-Oxy133; 20 mg Oxy133/graft), and 4) ACS with topically applied recombinant human bone morphogenetic protein-2 (rhBMP-2) dissolved in water (ACS-rhBMP-2; 5.0 μg rhBMP-2/graft). All animals underwent L4-L5 posterolateral spinal fusion. Spines were harvested 8 weeks postoperatively and analyzed using micro-computed tomography imaging.

RESULTS

Successful fusion was achieved in all animals. Grafts containing Oxy133 had significantly greater bone volume, percent of bone volume per tissue volume (%BV), bone surface density (BSD), and trabecular number (TbN) compared to ACS-rhBMP-2 (P < 0.01 for each). Animals treated with BioMim-Oxy133-Lo had the greatest %BV, BSD, and TbN (P < 0.001 for each), whereas animals treated with ACS-rhBMP-2 had the lowest %BV, BSD, TbN, and trabecular thickness (P < 0.001 for each).

CONCLUSIONS

BioMim-Oxy133 is a novel bone graft that led to superior bone volume and quality compared to ACS-rhBMP-2 in a clinically translatable rat model of spinal fusion. Future work is needed to further evaluate this material as a safe and efficacious bone graft substitute.

Synergistic enhancement of spinal fusion in preclinical models using low-dose rhBMP-2 and stromal vascular fraction in an injectable hydrogel composite

Spinal fusion surgery remains a significant challenge due to limitations in current bone graft materials, particularly in terms of bioactivity, integration, and safety. This study presents an innovative approach using an injectable hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) hydrogel combined with stromal vascular fraction (SVF) and low-dose recombinant human BMP-2 (rhBMP-2) to enhance osteodifferentiation and angiogenesis. Through a series of in vitro studies and preclinical models involving rats and minipigs, we demonstrated that the hydrogel system enables the sustained release of rhBMP-2, resulting in significantly improved bone density and integration, alongside reduced inflammatory responses. The combination of rhBMP-2 and SVF in this injectable formulation yielded superior spinal fusion outcomes, with enhanced mechanical properties and increased bone mass in both small and large animal models. These findings suggest that this strategy offers a promising and safer alternative for spinal fusion, with strong potential for clinical application.

Alveolar Bone Graft Supplemented With Stromal Vascular Fraction in Patients With Permanent Dentition: A Randomized Study

OBJECTIVE

To evaluate bone development in patients with alveolar clefts and permanent dentition treated with alveolar bone graft supplemented with stromal vascular fraction (SVF).

DESIGN

Clinical, prospective, randomized.

LOCATION

Single tertiary care institution.

PATIENTS

Eighteen participants with unilateral alveolar cleft and permanent dentition were included. Patients with other comorbidities were excluded.

INTERVENTION

The control group underwent alveolar bone grafting (ABG) using iliac crest bone, while the experimental group underwent the same treatment, supplemented with SVF. Adipose tissue was collected by abdominal liposuction, and the SVF was processed using mechanical methods (decantation, microfragmentation, and filtration).

MAIN OUTCOME MEASUREMENT

Bone formation and bone graft integration rate in alveolar cleft at 6 months postsurgery using 3-dimensional tomographic methods and density measurements.

RESULTS

The amount of bone graft correlated with an improvement in the relationship between the cleft and noncleft sides (R = 0.78, P < .001) and an improvement in alveolar cleft density (R = 0.69, P = .005), but did not correlate with the graft integration rate. The experimental group showed larger cleft sizes (0.83 × 1.74 cm3, P = .021) and older patients (17.35 × 27.6 years, P = .002), and did not differ in terms of bone development variables when compared to the control group.

CONCLUSION

ABG supplemented with SVF showed statistically similar bone development results, but with a better trend than conventional ABG. Additionally, the studied groups had asymmetric pre-existing characteristics, with greater severity in the experimental group. A larger study will be necessary to mitigate preoperative characteristic differences and to more accurately compare the results between the methods.

Synthesis and evaluation of a novel vancomycin-infused, biomimetic bone graft using a rat model of spinal implant-associated infection

Background

Postoperative infection is a complication of spinal fusion surgery resulting in increased patient morbidity. Strategies including intraoperative application of powdered vancomycin have been proposed to reduce the incidence of infection; however, such antimicrobial effects are short-lived.

Methods

Instrumentation of the L4-L5 vertebrae was performed mimicking pedicle screw and rod fixation in 30 rats. Titanium instrumentation inoculated with either PBS or 1×105 CFU bioluminescent MRSA, along with biomimetic bone grafts infused with varying concentrations of vancomycin and 125 µg of rhBMP-2 (BioMim-rhBMP-2-VCM) were implanted prior to closure. Infection was quantified during the six-week postoperative period using bioluminescent imaging. Arthrodesis was evaluated using micro-CT.

Results

Infected animals receiving a bone graft infused with low-dose (0.18 mg/g) or high-dose vancomycin (0.89 mg/g) both exhibited significantly lower bioluminescent signal over the six-week postoperative period than control animals inoculated with MRSA and implanted with bone grafts lacking vancomycin (p=.019 and p=.007, respectively). Both low and high-dose vancomycin-infused grafts also resulted in a statistically significant reduction in average bioluminescence when compared to control animals (p=.027 and p=.047, respectively), independent of time. MicroCT analysis of animals from each group revealed pseudoarthrosis only in the control group, suggesting a correlation between infection and pseudoarthrosis. MRSA-inoculated control animals also had significantly less bone volume formation on micro-CT than the PBS-inoculated control cohort (p<.001), the MRSA+low-dose vancomycin-infused bone graft cohort (p<.001), and the MRSA+high-dose vancomycin-infused bone graft cohort (p<.001).

Conclusion

BioMim-rhBMP-2-VCM presents a novel tissue engineering approach to simultaneously promoting arthrodesis and antimicrobial prophylaxis in spinal fusion. Despite mixed evidence of potential osteotoxicity of vancomycin reported in literature, BioMim-rhBMP-2-VCM preserved arthrodesis and osteogenesis with increasing vancomycin loading doses due to the graft's osteoinductive composition.

Analyzing the Clinical Potential of Stromal Vascular Fraction: A Comprehensive Literature Review

Background: Regenerative medicine is evolving with discoveries like the stromal vascular fraction (SVF), a diverse cell group from adipose tissue with therapeutic promise. Originating from fat cell metabolism studies in the 1960s, SVF's versatility was recognized after demonstrating multipotency. Comprising of cells like pericytes, smooth muscle cells, and, notably, adipose-derived stem cells (ADSCs), SVF offers tissue regeneration and repair through the differentiation and secretion of growth factors. Its therapeutic efficacy is due to these cells' synergistic action, prompting extensive research. Methods: This review analyzed the relevant literature on SVF, covering its composition, action mechanisms, clinical applications, and future directions. An extensive literature search from January 2018 to June 2023 was conducted across databases like PubMed, Embase, etc., using specific keywords. Results: The systematic literature search yielded a total of 473 articles. Sixteen articles met the inclusion criteria and were included in the review. This rigorous methodology provides a framework for a thorough and systematic analysis of the existing literature on SVF, offering robust insights into the potential of this important cell population in regenerative medicine. Conclusions: Our review reveals the potential of SVF, a heterogeneous cell mixture, as a powerful tool in regenerative medicine. SVF has demonstrated therapeutic efficacy and safety across disciplines, improving pain, tissue regeneration, graft survival, and wound healing while exhibiting immunomodulatory and anti-inflammatory properties.

A novel rodent model of chronic spinal implant-associated infection

BACKGROUND CONTEXT

Bacterial infection of spinal instrumentation is a significant challenge in spinal fusion surgery. Although the intraoperative local application of powdered vancomycin is common practice for mitigating infection, the antimicrobial effects of this route of administration are short-lived. Therefore, novel antibiotic-loaded bone grafts as well as a reliable animal model to permit the testing of such therapies are needed to improve the efficacy of infection reduction practices in spinal fusion surgery.

PURPOSE

This study aims to establish a clinically relevant rat model of spinal implant-associated infection to permit the evaluation of antimicrobial bone graft materials used in spinal fusion.

STUDY DESIGN

Rodent study of chronic spinal implant-associated infection.

METHODS

Instrumentation anchored in and spanning the vertebral bodies of L4 and L5 was inoculated with bioluminescent methicillin-resistant Staphylococcus aureus bacteria (MRSA). Infection was monitored using an in vivo imaging system (IVIS) for 8 weeks. Spines were harvested and evaluated histologically, and colony-forming units (CFUs) were quantified in harvested implants and spinal tissue.

RESULTS

Postsurgical analysis of bacterial infection in vivo demonstrated stratification between MRSA and phosphate-buffered saline (PBS) control groups during the first 4 weeks of the 8-week infection period, indicating the successful establishment of acute infection. Over the 8-week chronic infection period, groups inoculated with 1 × 105 MRSA CFU and 1 × 106 MRSA CFU demonstrated significantly higher bioluminescence than groups inoculated with PBS control (p = 0.009 and p = 0.041 respectively). Histological examination at 8 weeks postimplantation revealed the presence of abscesses localized to implant placement in all MRSA inoculation groups, with the most pervasive abscess formation in samples inoculated with 1 × 105 MRSA CFU and 1 × 106 MRSA CFU. Quantification of CFU plated from harvested spinal tissue at 8 weeks post-implantation revealed the 1 × 105 MRSA CFU inoculation group as the only group with a significantly greater average CFU count compared to PBS control (p = 0.017). Further, CFU quantification from harvested spinal tissue was greater than CFU quantification from harvested implants across all inoculation groups.

CONCLUSION

Our model demonstrated that the inoculation dosage of 1 × 105 MRSA CFU exhibited the most robust chronic infection within instrumented vertebral bodies. This dosage had the greatest difference in bioluminescence signal from control (p < 0.01), the lowest mortality (0% compared to 50% for samples inoculated with 1 × 106 MRSA CFU), and a significantly higher amount of CFUs from harvested spine samples than CFUs from control harvested spine samples. Further, histological analysis confirmed the reliability of this novel rodent model of implanted-associated infection to establish infection and biofilm formation of MRSA for all inoculation groups.

CLINICAL SIGNIFICANCE

This model is intended to simulate the infection of instrumentation used in spinal fusion surgeries concerning implant locality and material. This model may evaluate potential antimicrobial and osteogenic biomaterials and investigate the relationship between implant-associated infection and failed fusion.

Nanoparticles and Nanomaterials-Based Recent Approaches in Upgraded Targeting and Management of Cancer: A Review

Along with the extensive improvement in tumor biology research and different therapeutic developments, cancer remains a dominant and deadly disease. Tumor heterogeneity, systemic toxicities, and drug resistance are major hurdles in cancer therapy. Chemotherapy, radiotherapy, phototherapy, and surgical therapy are some prominent areas of cancer treatment. During chemotherapy for cancer, chemotherapeutic agents are distributed all over the body and also damage normal cells. With advancements in nanotechnology, nanoparticles utilized in all major areas of cancer therapy offer the probability to advance drug solubility, and stability, extend drug half-lives in plasma, reduce off-target effects, and quintessence drugs at a target site. The present review compiles the use of different types of nanoparticles in frequently and recently applied therapeutics of cancer therapy. A recent area of cancer treatment includes cancer stem cell therapy, DNA/RNA-based immunomodulation therapy, alteration of the microenvironment, and cell membrane-mediated biomimetic approach. Biocompatibility and bioaccumulation of nanoparticles is the major impediment in nano-based therapy. More research is required to develop the next generation of nanotherapeutics with the incorporation of new molecular entities, such as kinase inhibitors, siRNA, mRNA, and gene editing. We assume that nanotherapeutics will dramatically improve patient survival, move the model of cancer treatment, and develop certainty in the foreseeable future.