Treatment of medication-related osteonecrosis of the jaw with cell therapy.

Introduction: Medication-related osteonecrosis of the jaw (MRONJ) poses a significant challenge considering the absence of a "gold standard" treatment. Cell-based therapy and tissue engineering offer promising therapeutic alternatives. This study aimed to harness the regenerative properties of adipose-tissue stromal vascular fraction (AT-SVF) and leukocyte-platelet-rich fibrin (L-PRF) for MRONJ treatment. AT-SVF contains mesenchymal stromal cells (MSC) and endothelial progenitor cells (EPC), which promote bone formation, while the L-PRF scaffold can serve as a three-dimensional scaffold for the AT-SVF and support tissue healing through growth factor release. Materials and methods: The protocol involved applying autologous AT-SVF within an L-PRF matrix following surgical debridement. Age, gender, body mass index, comorbidities, underlying oncological condition, prescribed antiresorptive treatment: BP or DMB, antiresorptive treatment duration, antiresorptive treatment potential discontinuation, number of MRONJ lesion, MRONJ location, MRONJ stage, MRONJ trigger factor were assessed for each patient. Patients underwent the procedure and were monitored for a minimum of 6 months based on clinical, biological and medical imaging criteria. Results: Nine patients, with a total of ten MRONJ lesions, participated in the study. Six patients were female, and three were male, with a mean age of 68 ± 8 years. Four patients had multiple myeloma (MM), three had metastatic breast cancer, and two had metastatic prostate cancer. Seven MRONJ cases were classified as stage II, and three were classified as stage III. Soft tissue completely healed within a month after treatment in nine cases, with no clinical improvement observed in the remaining case. During follow-up, no sign of MRONJ recurrence was observed. Tridimensional medical imaging revealed bone healing 6 months after the surgical procedure. Immunophenotyping confirmed the presence of MSC and EPC in the AT-SVF: 12,6 ± 4,5% CD31+, 20.5 ± 7,8% CD34+, 34,4 ± 7,3% CD146+ and 54,6 ± 7,4% CD45+. Conclusion: This prospective study introduces a potential new treatment approach for MRONJ using autologous AT-SVF within an L-PRF scaffold. Our results are encouraging and suggest the need for further investigation with a larger patient cohort to better understand the underlying mechanisms.

Suburethral implantation of autologous regenerative cells for female stress urinary incontinence management: Results of a pilot study.

OBJECTIVES: To assess the feasibility and the safety of treating female stress urinary incontinence (SUI) with suburethral implantation of a mixture of the stromal vascular fraction from adipose tissue and leukocyte-and platelet-rich-fibrin. METHODS: Patients with SUI were treated with a mixture of stromal vascular fraction and leukocyte-and platelet-rich fibrin. The stromal vascular fraction was obtained from enzymatic digestion of autologous adipose-tissue and added to an leukocyte-and platelet-rich-fibrin membrane. The mixture was transvaginally implanted into the suburethral area. A fraction of the Stromal vascular fraction sample was used for cellular characterization. Patients were followed for 9 months. Every 3 months, the patients were clinically evaluated with a cough- stress test and a validated-questionnaire. An MRI was performed preoperatively and 3 months after the procedure to assess tissue changes. RESULTS: Ten patients received the surgical procedure. The validated-questionnaire revealed a subjective SUI improvement in nine patients 3 months after the operation and in seven patients 9 months after the operation. Eight, six, and four patients achieved a negative cough-stress test 3, 6 and 9 months post-injection, respectively. Flow cytometric analysis of stromal vascular fraction cell phenotypes revealed predominantly mesenchymal and endothelial cell heterogeneity. In total, we injected 0,18 × 106 to 13,6 × 106 cells. No adverse events were observed peri- or postoperatively. CONCLUSION: These preliminary results suggest that the suburethral implantation of a combination of SVF and l-PRF is a feasible and safe modality for treating female SUI. However, evidence is lacking and further research are needed to clarify the respective roles of SVF and l-PRF in female SUI treatment.

Cross-Talk Between Mesenchymal Stromal Cells (MSCs) and Endothelial Progenitor Cells (EPCs) in Bone Regeneration.

Bone regeneration is a complex, well-orchestrated process based on the interactions between osteogenesis and angiogenesis, observed in both physiological and pathological situations. However, specific conditions (e.g., bone regeneration in large quantity, immunocompromised regenerative process) require additional support. Tissue engineering offers novel strategies. Bone regeneration requires a cell source, a matrix, growth factors and mechanical stimulation. Regenerative cells, endowed with proliferation and differentiation capacities, aim to recover, maintain, and improve bone functions. Vascularization is mandatory for bone formation, skeletal development, and different osseointegration processes. The latter delivers nutrients, growth factors, oxygen, minerals, etc. The development of mesenchymal stromal cells (MSCs) and endothelial progenitor cells (EPCs) cocultures has shown synergy between the two cell populations. The phenomena of osteogenesis and angiogenesis are intimately intertwined. Thus, cells of the endothelial line indirectly foster osteogenesis, and conversely, MSCs promote angiogenesis through different interaction mechanisms. In addition, various studies have highlighted the importance of the microenvironment via the release of extracellular vesicles (EVs). These EVs stimulate bone regeneration and angiogenesis. In this review, we describe (1) the phenomenon of bone regeneration by different sources of MSCs. We assess (2) the input of EPCs in coculture in bone regeneration and describe their contribution to the osteogenic potential of MSCs. We discuss (3) the interaction mechanisms between MSCs and EPCs in the context of osteogenesis: direct or indirect contact, production of growth factors, and the importance of the microenvironment via the release of EVs.

Isolation and Characterization of Human Mesenchymal Stromal Cell Subpopulations: Comparison of Bone Marrow and Adipose Tissue.

Preparations of mesenchymal stromal cells (MSCs) are generally obtained from unfractionated tissue cells, resulting in heterogeneous cell mixtures. Several markers were proposed to enrich these cells, but the majority of these markers are defined for bone marrow (BM). Moreover, the surface markers of freshly isolated MSCs also differ from those of cultured MSCs in addition to a phenotypic variation depending on the MSC source. For tissue engineering applications, it is crucial to start with a well-defined cell population. In this study, we performed immunomagnetic selections with five single surface markers to isolate MSC subpopulations from BM and adipose tissue (AT): CD271, SUSD2, MSCA-1, CD44, and CD34. We determined the phenotype, the clonogenicity, the proliferation, the differentiation capacity, and the immunoregulatory profile of the subpopulations obtained in comparison with unselected cells. We showed that native BM-MSCs can be enriched from the positive fractions of MSCA-1, SUSD2, and CD271 selections. In contrast, we observed that SUSD2 and MSCA-1 were unable to identify MSCs from AT, meaning they are not expressed in situ. Only the CD34(+) selection successfully isolated MSCs from AT. Interestingly, we observed that CD271 selection can define AT cell subsets with particular abilities, but only in lipoaspiration samples and not in abdominoplasty samples. Importantly, we found a population of clear CD34(+) fresh BM-MSCs displaying different properties. A single marker-based selection for MSC enrichment should be more advantageous for cell therapy and would enable the standardization of efficient and safe therapeutic intervention through the use of a well-identified and homogeneous cell population.

In vivo production of mesenchymal stromal cells after injection of autologous platelet-rich plasma activated by recombinant human soluble tissue factor in the bone marrow of healthy volunteers.

Autologous mesenchymal stromal cell (MSC)-based therapies offer one of the most promising and safe methods for regeneration or reconstruction of tissues and organs. Routine procedures to obtain adequate amount of autologous stem cells need their expansion through culture, with risks of contamination and cell differentiation, leading to the loss of cell ability for therapies. We suggest the use of human bone marrow (BM) as a physiological bioreactor to produce autologous MSC by injection of autologous platelet-rich plasma activated by recombinant human soluble tissue factor (rhsTF) in iliac crest. A trial on 13 healthy volunteers showed the feasibility and harmlessness of the procedure. The phenotype and cellularity of BM cells were not modified, on day 3 after injection. Endothelial progenitor cells (EPC) were mobilized to the bloodstream, without stimulation of hematopoietic stem cells (HSC). MSC level in BM increased with a specific commitment to preosteoblastic cell population both in vivo and in vitro. This self-stimulation system of BM seems thus to be a promising feasible process 3 days before clinical cell therapy applications.

Tissue factor: a mini-review.

Tissue factor (TF) is historically known as the trigger of the coagulation cascade. This integral membrane glycoprotein forms a ternary complex with factor VIIa (FVIIa) and zymogen factor (FX), which is then activated to factor Xa (FXa). The latter cleaves prothrombin into thrombin (FIIa), which in turn activates fibrinogen in fibrin monomers. What is less known is its additional non-haemostatic roles in inflammation, tumour growth and angiogenesis. This aspect will be developed here. TF, as a transmembrane protein, has a signalling effect requiring FVIIa. TF-FVIIa complex activates G protein-coupled receptor protease-activated receptor 2 (PAR-2) and therefore modulates various cellular processes, such as cell proliferation and survival, gene transcription and protein translation. In this review we will first highlight, using recent structural data, the 'potentially' active domain able to modulate the triggered intracellular response. We also will focus on the still emerging and promising results deciphering the diverse locations in which TF appears. We conclude with a description of an emerging and atypical use of tissue factor in platelet gel surgery for sinus augmentation.

Sinus grafting using recombinant human tissue factor, platelet-rich plasma gel, autologous bone, and anorganic bovine bone mineral xenograft: histologic analysis and case reports.

PURPOSE: The purpose of this study was to analyze healthy bone formation by means of histology and immunohistochemistry after grafting with a mixture of autologous ground calvarial bone, inorganic xenograft, platelet-rich plasma (PRP), and recombinant human tissue factor (rhTF). MATERIALS AND METHODS: Maxillary sinus floor augmentation was performed on 3 patients by grafting with 5 to 10 mL of a paste consisting of autologous powder from calvarial bone (diameter < 1 mm), 50% v/v anorganic bovine bone mineral xenograft (PepGen P-15, a new tissue-engineered bone replacement graft material), PRP (1.8 x 10(6) platelets/mm3 plasma), and about 1 microg rhTF. Six and 10 months after grafting, bone cores were extracted for implant fixation and analyzed. RESULTS: Histology demonstrated a high degree of inorganic xenograft integration and natural bone regeneration. Both the xenograft and newly synthesized bone were colonized with osteocytes and surrounded by osteoblasts. Six-month-old bone cores demonstrated a ratio of synthesized bone to xenograft particles ratio of 0.5, whereas 10-month-old cores demonstrated a ratio of 2. A low degree of inflammation could also be observed using S100A8 immunohistochemistry. DISCUSSION: Autologous grafting in edentulous patients is a complex procedure; the successful substitution of synthetic analogs for ground bone is a major challenge. CONCLUSION: In this investigation, it was shown that inorganic xenograft in the harvested bone paste could be safe for patients and had high bone regeneration capacity over time. The sinus graft showed intense bone formation 6 months after grafting and a further increase in bone growth 10 months after grafting.

Human recombinant tissue factor, platelet-rich plasma, and tetracycilne induce a high-quality human bone graft: a 5-year survey.

PURPOSE: To increase human bone graft regeneration and quality by the use of a mixture containing autologous ground calvarial bone, human recombinant tissue factor (rhTF), platelet-rich plasma (PRP), and tetracycline. MATERIALS AND METHODS: Maxillary sinus floor augmentation was performed on 18 patients by grafting a "bone paste" made of PRP (1.8 x 10(6) platelets/mm3 plasma), about 1 microg rhTF, calvarial bone chips (2 to 5 mm in size), and tetracycline (10 to 30 microg/mL preparation). Five to 6 months after the surgical phase and grafting a bone core was extracted for implant fixation, and the osseous core samples were analyzed microscopically. RESULTS: Histology revealed vascularized connective tissue rich in lamellar bone spicules containing osteocytes and surrounded by osteoblasts. The success rate of grafting was 90.3%. In 6-month postoperative blood samples, no residual coagulating disturbances could be found. DISCUSSION: The combination of calvarial bone chips, rhTF, PRP, and tetracycline results in a paste that is easy to handle, safe for patients, and possesses high bone-regeneration capacity. CONCLUSION: The generalized use in implant dentistry, oral surgery, and orthopedics of such a protocol could facilitate the healing process as well as patient safety and surgeon comfort.