Scaffold-based delivery of autologous mesenchymal stem cells for mandibular distraction osteogenesis: preliminary studies in a porcine model

Enhancement of Vascularization and Ovarian Follicle Survival Using Stem Cells in Cryopreserved Ovarian Tissue Transplantation-A Systematic Review

The increase in cancer survival rates has put a focus on ensuring fertility preservation procedures for cancer patients. Ovarian tissue cryopreservation presents the only option for prepubertal girls and patients who require immediate start of treatment and, therefore, cannot undergo controlled ovarian stimulation. We aimed to provide an assessment of stem cells' impact on cryopreserved ovarian tissue grafts in regard to the expression of growth factors, angiogenesis promotion, tissue oxygenation, ovarian follicle survival and restoration of endocrine function. For this systematic review, we searched the Scopus and PubMed databases and included reports of trials using murine and/or human cryopreserved ovarian tissue for transplantation or in vitro culture in combination with mesenchymal stem cell administration to the grafting site. Of the 1201 articles identified, 10 met the criteria. The application of stem cells to the grafting site has been proven to support vascular promotion and thereby shorten the period of tissue hypoxia, which is reflected in the increased number of remaining viable follicles and faster recovery of ovarian endocrine function. Further research is needed before implementing the use of stem cells in OT cryopreservation and transplantation procedures in clinical practice. Complex ethical dilemmas make this process more difficult.

FGF2/HGF priming facilitates adipose-derived stem cell-mediated bone formation in osteoporotic defects

Aims

The activity of adipose-derived stem cells (ADSCs) is susceptible to the physiological conditions of the donor. Therefore, employing ADSCs from donors of advanced age or with diseases for cell therapy necessitates a strategy to enhance therapeutic efficacy before transplantation. This study aims to investigate the impact of supplementing Fibroblast Growth Factor 2 (FGF2) and Hepatocyte Growth Factor (HGF) on ADSC-mediated osteogenesis under osteoporotic conditions and to explore the underlying mechanisms of action.

Main methods

Adipose-derived stem cells (ADSCs) obtained from ovariectomized (OVX) rats were cultured ex vivo. These cells were cultured in an osteogenic medium supplemented with FGF2 and HGF and subsequently autologously transplanted into osteoporotic femur defects using Hydroxyapatite-Tricalcium Phosphate. The assessment of bone formation was conducted four weeks post-transplantation.

Key findings

Osteoporosis detrimentally affects the viability and osteogenic differentiation potential of ADSCs, often accompanied by a deficiency in FGF2 and HGF signaling. However, priming with FGF2 and HGF facilitated the formation of immature osteoblasts from OVX ADSCs in vitro, promoting the expression of osteoblastogenic proteins, including Runx-2, osterix, and ALP, during the early phase of osteogenesis. Furthermore, FGF2/HGF priming augmented the levels of VEGF and SDF-1α in the microenvironment of OVX ADSCs under osteogenic induction. Importantly, transplantation of OVX ADSCs primed with FGF2/HGF for 6 days significantly enhanced bone formation compared to non-primed cells. The success of bone regeneration was confirmed by the expression of type-1 collagen and osteocalcin in the bone tissue of the deficient area.

Significance

Our findings corroborate that priming with FGF2/HGF can improve the differentiation potential of ADSCs. This could be applied in autologous stem cell therapy for skeletal disease in the geriatric population.

Priming with a Combination of FGF2 and HGF Restores the Impaired Osteogenic Differentiation of Adipose-Derived Stem Cells

Classical aging-associated diseases include osteoporosis, diabetes, hypertension, and arthritis. Osteoporosis causes the bone to become brittle, increasing fracture risk. Among the various treatments for fractures, stem cell transplantation is currently in the spotlight. Poor paracrine/differentiation capacity, owing to donor age or clinical history, limits efficacy. Lower levels of fibroblast growth factor 2 (FGF2) and hepatocyte growth factor (HGF) are involved in cell repopulation, angiogenesis, and bone formation in the elderly ADSCs (ADSC-E) than in the young ADSCs (ADSC-Y). Here, we study the effect of FGF2/HGF priming on the osteogenic potential of ADSC-E, determined by calcium deposition in vitro and ectopic bone formation in vivo. Age-induced FGF2/HGF deficiency was confirmed in ADSCs, and their supplementation enhanced the osteogenic differentiation ability of ADSC-E. Priming with FGF2/HGF caused an early shift of expression of osteogenic markers, including Runt-related transcription factor 2 (Runx-2), osterix, and alkaline phosphatase (ALP) during osteogenic differentiation. FGF2/HGF priming also created an environment favorable to osteogenesis by facilitating the secretion of bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF). Bone tissue of ADSC-E origin was observed in mice transplanted with FGF/HGF-primed ADSC-E. Collectively, FGF2/HGF priming could enhance the bone-forming capacity in ADSC-E. Therefore, growth factor-mediated cellular priming can enhance ADSC differentiation in bone diseases and thus contributes to the increased efficacy in vivo.

Effects of porcine bone marrow-derived platelet-rich plasma on bone marrow-derived mesenchymal stem cells and endothelial progenitor cells

This study investigated the abundance of pro-regenerative growth factors in bone marrow-derived platelet-rich plasma (BM-PRP) and their effects on bone marrow-derived mesenchymal stem cells (BM-MSC) and bone marrow-derived endothelial progenitor cells (BM-EPC). Four 4-5 months-old domestic pigs were included, and each underwent bone marrow aspiration from its humerus bones and processed into bone marrow aspiration concentrate (BMAC) samples. The plasma and cellular portions of BMAC were subsequently separated and collected. The concentration of growth factors including BMP-2, PDGF-BB, TGF-β1 and VEGF in the plasma portion was measured and compared between BM-PRP and bone marrow-derived platelet-poor plasma (BM-PPP). It was found that platelet count was significantly higher in BM-PRP than in BM-PPP, but the concentration of above-mentioned growth factors was not significantly different between BM-PRP and BM-PPP. As most existing literature has indicated the regenerative potency of PRP, this study focused on assessing the effect of BM-PRP treatment on BM-MSC and BM-EPC proliferation, osteogenic differentiation and angiogenesis capacity by comparing samples with 2.5% BM-PRP treatment and samples without BM-PRP treatment (control). In response to BM-PRP treatment, the cellular doubling time increased with culturing time and was significantly shorter in the BM-PRP-treated samples than in control samples. For osteogenic differentiation, BM-PRP-treated BM-MSCs demonstrated a time-dependent increase in alkaline phosphatase (ALP) activity and expression levels of osteogenic differentiation markers. For the expression of angiogenic genes, none of the differences reached statistical significance despite a tendency of stronger expression at day 18 in BM-PRP-treated BM-EPCs. In conclusion, this in vitro study suggests that most BMP-2, PDGF-BB, TGF-β1 and VEGF-A contained in BM-PRP are not platelet-released and BM-PRP may have some stimulation (less than 1-fold) for MSC, EPC proliferation and MSC osteogenic differentiation.

Overview of methods for enhancing bone regeneration in distraction osteogenesis: Potential roles of biometals

BACKGROUND

Distraction osteogenesis (DO) is a functional tissue engineering approach that applies gradual mechanical traction on the bone tissues after osteotomy to stimulate bone regeneration. However, DO still has disadvantages that limit its clinical use, including long treatment duration.

METHODS

Review the current methods of promoting bone formation and consolidation in DO with particular interest on biometal.

RESULTS

Numerous approaches, including physical therapy, gene therapy, growth factor-based therapy, stem-cell-based therapy, and improved distraction devices, have been explored to reduce the DO treatment duration with some success. Nevertheless, no approach to date is widely accepted in clinical practice due to various reasons, such as high expense, short biologic half-life, and lack of effective delivery methods. Biometals, including calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), manganese (Mn), and cobalt (Co) have attracted attention in bone regeneration attributed to their biodegradability and bioactive components released during in vivo degradation.

CONCLUSION

This review summarizes the current therapies accelerating bone formation in DO and the beneficial role of biometals in bone regeneration, particularly focusing on the use of biometal Mg and its alloy in promoting bone formation in DO. Translational potential: The potential clinical applications using Mg-based devices to accelerate DO are promising. Mg stimulates expression of multiple intrinsic biological factors and the development of Mg as an implantable component in DO may be used to argument bone formation and consolidation in DO.

Local administration of allogeneic or autologous bone marrow-derived mesenchymal stromal cells enhances bone formation similarly in distraction osteogenesis

BACKGROUND AIMS

Distraction osteogenesis (DO) is a surgical technique to promote bone regeneration that requires a long time for bone healing. Bone marrow-derived mesenchymal stromal cells (MSCs) have been applied to accelerate bone formation in DO. Allogeneic MSCs are attractive, as they could be ready to use in clinics. Whether allogeneic MSCs would have an effect similar to autologous MSCs with regard to promoting bone formation in DO is still unknown. This study compares the effect of autologous MSCs versus allogeneic MSCs on bone formation in a rat DO model.

METHODS

Rat bone marrow-derived MSCs were isolated, characterized and expanded in vitro. Adult rats were subjected to right tibia transverse osteotomy. On the third day of distraction, each rat received one injection of phosphate-buffered saline (PBS), autologous MSCs or allogeneic MSCs at the distraction site. Tibiae were harvested after 28 days of consolidation for micro-computed tomography examination, mechanical test and histological analysis.

RESULTS

Results showed that treatment with both allogeneic and autologous MSCs promoted bone formation, with significantly higher bone mass, mechanical properties and mineral apposition rate as well as expression of angiogenic and bone formation markers at the regeneration sites compared with the PBS-treated group. No statistical difference in bone formation was found between the allogeneic and autologous MSC treatment groups.

CONCLUSIONS

This study indicates that allogeneic and autologous MSCs have a similar effect on promoting bone consolidation in DO. MSCs from an allogeneic source could be used off-the-shelf with DO to achieve early bone healing.

Xenogeneic mesenchymal stem cell transplantation for mandibular defect regeneration

BACKGROUND

It is commonly accepted that xenogeneic stem cell transplantation for tissue engineering is faced with host immune rejection. Using a rat critical-size mandibular defect model, this study examined whether the immune rejection can be evaded by diminishing T-cell immunity.

METHODS

To examine donor cell survival and host immune reaction, pig bone marrow-derived mesenchymal stem cells (BM-MSCs) were labeled with CM-DiI, loaded onto gelatin sponge (5 × 10⁶ cells/scaffold), and transplanted into 5-mm mandibular defects of immunocompetent and T cell-deficient athymic rats. To examine the effects of xenogeneic BM-MSCs on bone regeneration, athymic rats undergone the same surgeries were terminated at post-operative weeks 1, 3, and 6. Control rats underwent the same jaw surgery without BM-MSC transplantation.

RESULTS

The density of CM-DiI-labeled BM-MSCs decreased with time in both strains of rats. Although it was substantially higher in athymic rats than in immunocompetent rats at post-operative day 1, by day 3-7 the density became comparable between the two strains of rats. Apoptosis reflected by cleaved Caspase-3 staining was low in both strains. Stronger infiltration of neutrophils, macrophages, B cells and CD8⁺ T cells was found in MSC-treated animals. In athymic rats, infiltration of neutrophils and macrophages was strong, but it occurred later than that in immunocompetent rats. While bone volume fraction significantly increased with time (P < .001), no difference was found between MSC-treated and control groups.

CONCLUSIONS

Even in hosts with deficient T-cell immunity, xenogeneic BM-MSC transplantation into mandibular critical-sized defects still faces challenges from host innate immunity, which compromises their regenerative efficacy.

Enhance Mandibular Symphyseal Surface Bone Growth with Autologous Mesenchymal Stem Cell Sheets: An Animal Study

INTRODUCTION

The size and shape of the chin strongly influence facial profile and harmony. The current correction of chin deficiency mostly relies on genioplasty surgery involving osteotomy. To avoid osteotomy, one possible alternative is to enhance bone growth at the mental protuberance area with cell sheet transplantation. This study was undertaken to evaluate the efficacy of this approach in a pig model.

MATERIALS AND METHODS

Five 4-month-old pigs were included for mandibular bone marrow aspiration and MSC isolation. Triple-layer MSC sheets were then fabricated and utilized using culture-expanded MSCs. Four weeks after bone marrow aspiration, subperiosteal pockets were created on the labial symphyseal surface, followed by transplantation of autogenous MSC sheets to one randomly chosen side with the other side (control) receiving no transplantation. Six weeks after the surgery, the pigs were euthanized and the specimens from both sides were collected for computed tomography (CT) and histological and immunohistochemical analysis. Measurements between the experimental and control sides were compared using paired t tests.

RESULTS

MSC sheet fabrication and transplantation were reliably conducted. The labial cortical bone thickness increased significantly with MSC sheet transplantation by an average of 2 mm (p = 0.0001). The average measurements of mineral apposition rate and cell proliferation at the cell sheet side tended to be higher than the control side although the differences did not reach statistical significance (p = 0.1-0.2). Tissue mineral density measurements from CT images and bone volume fraction (BV/TV) measurements from histologic images were identical between the two sides (p > 0.5).

CONCLUSION

These data provide a proof of concept that autologous MSC sheets may be transplanted to the subperiosteal region of the mandibular symphysis to stimulate local surface bone growth.

NO LEVEL ASSIGNED

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Cephalometric studies of the mandible, its masticatory muscles and vasculature of growing Göttingen Minipigs-A comparative anatomical study to refine experimental mandibular surgery

Over many decades, the Göttingen Minipig has been used as a large animal model in experimental surgical research of the mandible. Recently several authors have raised concerns over the use of the Göttingen Minipig in this research area, observing problems with post-operative wound healing and loosening implants. To reduce these complications during and after surgery and to improve animal welfare in mandibular surgery research, the present study elucidated how comparable the mandible of minipigs is to that of humans and whether these complications could be caused by specific anatomical characteristics of the minipigs' mandible, its masticatory muscles and associated vasculature. Twenty-two mandibular cephalometric parameters were measured on CT scans of Göttingen Minipigs aged between 12 and 21 months. Ultimately, we compared this data with human data reported in the scientific literature. In addition, image segmentation was used to determine the masticatory muscle morphology and the configuration of the mandibular blood vessels. Compared to data of humans, significant differences in the mandibular anatomy of minipigs were found. Of the 22 parameters measured only four were found to be highly comparable, whilst the others were not. The 3D examinations of the minipigs vasculature showed a very prominent deep facial vein directly medial to the mandibular ramus and potentially interfering with the sectional plane of mandibular distraction osteogenesis. Damage to this vessel could result in inaccessible bleeding. The findings of this study suggest that Göttingen Minipigs are not ideal animal models for experimental mandibular surgery research. Nevertheless if these minipigs are used the authors recommend that radiographic techniques, such as computed tomography, be used in the specific planning procedures for the mandibular surgical experiments. In addition, it is advisable to choose suitable age groups and customize implants based on the mandibular dimensions reported in this study.

Dental pulp stem cells expressing SIRT1 improve new bone formation during distraction osteogenesis

Distraction osteogenesis (DO) is one of the most promising reconstructive methods for repairing large craniofacial defects or growth deficiencies through bone regeneration, but it is also a challenge because of an undesirably long process and its complications, which limit its application in clinical practice. The transplantation of mesenchymal stem cells (MSCs) is regarded as an innovative approach to accelerate bone regeneration. Dental pulp stem cells (DPSCs) have shown some advantages over other human adult MSCs, and DPSCs have been regarded as one of the most promising cell sources used in the endogenous tissue engineering. Furthermore, using stem cells modified by gene engineering in DO has been reported in previous studies. It has been shown that Sirtuin-1 (SIRT1) can directly regulate the differentiation of MSCs into osteoblasts. In this study, DPSCs expressing SIRT1 were prepared and their effects on the new bone formation were further investigated in rabbits with tibia. Rabbits were injected with the adenovirus (Adv)-SIRT1-green fluorescent protein (GFP)-transfected DPSCs (overexpression group, Group OE), Adv-GFP transfected DPSCs (negative control group, Group NC) or physiologic saline (control group, Groups CON) into the distraction gap. The new bone tissues in the distraction gap were harvested 8 weeks later, and subjected to by radiographic examination, micro-CT evaluation, and histological and mechanical testing. The better bone formation, the highest bone mineral density (BMD) and the highest bone mineral content (BMC) were observed in the OE group. In conclusion, SIRT1-modified DPSCs in DO was more effective to promote new bone formation during DO, which provides evidence for further investigation about the role of of SIRT1 in the DO.

Applications of stem cells in orthodontics and dentofacial orthopedics: Current trends and future perspectives

A simple overview of daily orthodontic practice involves use of brackets, wires and elastomeric modules. However, investigating the underlying effect of orthodontic forces shows various molecular and cellular changes. Also, orthodontics is in close relation with dentofacial orthopedics which involves bone regeneration. In this review current and future applications of stem cells (SCs) in orthodontics and dentofacial orthopedics have been discussed. For craniofacial anomalies, SCs have been applied to regenerate hard tissue (such as treatment of alveolar cleft) and soft tissue (such as treatment of hemifacial macrosomia). Several attempts have been done to reconstruct impaired temporomandibular joint. Also, SCs with or without bone scaffolds and growth factors have been used to regenerate bone following distraction osteogenesis of mandibular bone or maxillary expansion. Current evidence shows that SCs also have potential to be used to regenerate infrabony alveolar defects and move the teeth into regenerated areas. Future application of SCs in orthodontics could involve accelerating tooth movement, regenerating resorbed roots and expanding tooth movement limitations. However, evidence supporting these roles is weak and further studies are required to evaluate the possibility of these ideas.

Combined effect of retinoic acid and calcium on the in vitro differentiation of human adipose-derived stem cells to adipocytes

CONTEXT

It has been shown that adipogenesis can be modulated by factors such as all-trans retinoic acid (ATRA) and calcium.

OBJECTIVE

To determine, the combined effect of ATRA and calcium on the differentiation of human adipose-derived stem cells (hADSCs).

METHODS

Mesenchymal stem cells (MSCs) were differentiated into the adipocytes by 0.5 and 1 µM of ATRA and 5 and 10 mM calcium separately or in combination. After MTS assay the differentiation of MSCs to adipocyte was evaluated, Oil Red O staining, GLUT4 concentration and gene expression of PPARG2, adiponectin, and GLUT4 were measured by Real-Time PCR.

RESULTS

Except 10 mM calcium treated group, other groups and more significantly combination treatments could reduce all adipocyte markers compared to the control.

CONCLUSION

These results suggest that ATRA and calcium together have significant inhibitory effect on adipogenesis that can be helpful for finding new mechanisms to prevent or control the adipogenesis.

The Effect of Bone Marrow Mesenchymal Stem Cells Application on Distracted Bone Quality during Rapid Rate of Distraction Osteogenesis

Distraction osteogenesis (DO) bone regenerate usually suffers from an inferior quality especially with rapid rate. This study was conducted to investigate the effect of mesenchymal stem cells (MSCs) application on different rates of distraction bone quality. Twenty-four goats were divided into group A with standard DO and group B with rapid distraction osteogenesis (RDO) both aided by MSCs. Group C with standard DO and group (D) with RDO were controls. Kruskal-Wallis test and Conover's post hoc analysis was used to evaluate significance ( p  = 0.05). Histomorphometry showed a strongly significant (SS) increase ( p  = 0.00036) in trabecular bone (TB) in group A (TB = 174.7 µm, SD = 33.5) and group B (TB = 166.8 µm, SD = 14) compared with group C (TB = 115.4 µm, SD = 19.6) and group D (TB = 86.1 µm, SD = 9.3). There was SS decrease ( p  = 0.00093) in osteoid percentage (OP) in group A (OP = 13.4%, SD = 2) and group B (OP = 11.5%, SD = 6.5) compared with group C (OP = 27.3, SD = 3.5) and group D (OP = 26.2%, SD = 2.6). Energy dispersive X-ray showed a nonsignificant increase ( p  = 0.11) in calcification (Ca ²⁺ %) in group A (Ca ²⁺ % = 17.6%, SD = 4.9) and group B (Ca ²⁺ % = 17.6%, SD = 4.3) compared with group C (Ca ²⁺ % = 14.2%, SD = 6.7) and group D (Ca ²⁺ % = 11.5%, SD = 2.4). MSCs application improved microscopic bone quality during standard DO and RDO. However, macroscopic bone quality improvement still needs further investigation.

Similarities and differences between porcine mandibular and limb bone marrow mesenchymal stem cells

OBJECTIVE

Research has shown promise of using bone marrow mesenchymal stem cells (BMSCs) for craniofacial bone regeneration; yet little is known about the differences of BMSCs from limb and craniofacial bones. This study compared pig mandibular and tibia BMSCs for their in vitro proliferation, osteogenic differentiation properties and gene expression.

DESIGN

Bone marrow was aspirated from the tibia and mandible of 3-4 month-old pigs (n=4), followed by BMSC isolation, culture-expansion and characterization by flow cytometry. Proliferation rates were assessed using population doubling times. Osteogenic differentiation was evaluated by alkaline phosphatase activity. Affymetrix porcine microarray was used to compare gene expressions of tibial and mandibular BMSCs, followed by real-time RT-PCR evaluation of certain genes.

RESULTS

Our results showed that BMSCs from both locations expressed MSC markers but not hematopoietic markers. The proliferation and osteogenic differentiation potential of mandibular BMSCs were significantly stronger than those of tibial BMSCs. Microarray analysis identified 404 highly abundant genes, out of which 334 genes were matched between the two locations and annotated into the same functional groups including osteogenesis and angiogenesis, while 70 genes were mismatched and annotated into different functional groups. In addition, 48 genes were differentially expressed by at least 1.5-fold difference between the two locations, including higher expression of cranial neural crest-related gene BMP-4 in mandibular BMSCs, which was confirmed by real-time RT-PCR.

CONCLUSIONS

Altogether, these data indicate that despite strong similarities in gene expression between mandibular and tibial BMSCs, mandibular BMSCs express some genes differently than tibial BMSCs and have a phenotypic profile that may make them advantageous for craniofacial bone regeneration.

Stem and progenitor cells: advancing bone tissue engineering

Unlike many other postnatal tissues, bone can regenerate and repair itself; nevertheless, this capacity can be overcome. Traditionally, surgical reconstructive strategies have implemented autologous, allogeneic, and prosthetic materials. Autologous bone--the best option--is limited in supply and also mandates an additional surgical procedure. In regenerative tissue engineering, there are myriad issues to consider in the creation of a functional, implantable replacement tissue. Importantly, there must exist an easily accessible, abundant cell source with the capacity to express the phenotype of the desired tissue, and a biocompatible scaffold to deliver the cells to the damaged region. A literature review was performed using PubMed; peer-reviewed publications were screened for relevance in order to identify key advances in stem and progenitor cell contribution to the field of bone tissue engineering. In this review, we briefly introduce various adult stem cells implemented in bone tissue engineering such as mesenchymal stem cells (including bone marrow- and adipose-derived stem cells), endothelial progenitor cells, and induced pluripotent stem cells. We then discuss numerous advances associated with their application and subsequently focus on technological advances in the field, before addressing key regenerative strategies currently used in clinical practice. Stem and progenitor cell implementation in bone tissue engineering strategies have the ability to make a major impact on regenerative medicine and reduce patient morbidity. As the field of regenerative medicine endeavors to harness the body's own cells for treatment, scientific innovation has led to great advances in stem cell-based therapies in the past decade.

Scaffold-Based Delivery of Bone Marrow Mesenchymal Stem Cell Sheet Fragments Enhances New Bone Formation In Vivo

PURPOSE

Stem cell therapy is becoming a potent strategy to shorten the consolidation time and reduce potential complications during distraction osteogenesis (DO). However, the conventional local injection or scaffold-based delivery of bone marrow mesenchymal stem cell (BMSC) suspension deprives the cells of their endogenous extracellular matrix, which might dampen cell differentiation and tissue regeneration after implantation. Therefore, in our study, a BMSC sheet was established and was then minced into fragments and loaded onto a hydroxyapatite (HA) scaffold for grafting.

MATERIALS AND METHODS

The purified and characterized BMSCs were grown into a cell sheet, and bone formation and mineralization capacity, as well as the cell sheet composition, were analyzed. Afterward, the in vivo osteogenic ability of cell sheet fragments (CSFs) was evaluated in immunocompromised mouse and rabbit models of DO.

RESULTS

The BMSC sheet exhibited higher alkaline phosphatase activity than osteogenic cell suspension cultures. Alkaline phosphatase activity and mineral particles in the cell sheet increased further after osteogenic induction. Moreover, calcium and phosphorus were present only in the osteogenic cell sheet, along with the common elements carbon, oxygen, chlorine, sodium, and sulfur, as indicated by x-ray photoelectron spectroscopy analysis. In a mouse model, the CSF-HA complex was injected subcutaneously. Micro-computed tomography analysis showed that the osteogenic CSF-HA complex led to a considerably higher bone volume than the BMSC-HA or CSF-HA complex. The osteogenic CSF-HA specimens showed increased angiogenesis and deposition of type I collagen compared with the non-osteogenic CSF-HA or BMSC-HA specimens. Moreover, the osteogenic CSF-HA markedly improved bone consolidation and increased bone mass in DO rabbits.

CONCLUSIONS

Collectively, the incorporation of osteogenic BMSC sheets into HA particles greatly promoted bone regeneration, which offers therapeutic alternatives for DO.

Mandibular distraction osteogenesis assisted by cell-based tissue engineering: a systematic review

OBJECTIVES

To review the advances and limitations of recent investigations on mandibular distraction osteogenesis (MDO) assisted by mesenchymal stem cell (MSC) transplantation.

MATERIALS AND METHODS

Following the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines, the PubMed, Scopus, and Cochrane electronic databases were systematically searched and screened from their inception through August 2014. Searching terms included the following: 'distraction osteogenesis', 'mandible OR mandibular OR jaw', and 'cells', without any other limitations.

RESULTS

Nineteen studies meeting the eligibility criteria were selected from 227 published articles and used for qualitative synthesis. Fifteen of the studies used small animal models (rats or rabbits), while the other four used large animal models (dogs, pigs or sheep). Among these studies, large variations exist in MDO protocol, cell transplantation time, route and quantity, as well as methodology of outcome assessment. Additionally, all studies had certain biases. Nevertheless, the majority of studies found that MSC transplantation enhanced MDO bone regeneration.

CONCLUSION

Evidence from animal studies indicates that MDO may be enhanced by mesenchymal stem cell transplantation, but many questions related to animal models, MDO protocols, and cell transplantation remain to be investigated.

Reconstructing jaw defects with MSCs and PLGA-encapsulated growth factors

Cell and growth factor-based tissue engineering has shown great potentials for skeletal regeneration. This study tested its feasibility in reconstructing large mandibular defects and compared the efficacy of varied construction materials and sealing methods. Bilateral mandibular critical-size (5-cm(3)) defects were created on six 4-month-old domestic pigs, and grafted with β-tricalcium phosphate (βTCP) only (Group-A), βTCP with autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) (Group-B), and βTCP with BM-MSCs and biodegradable poly(lactic-co-glycolic acid) (PLGA) microspheres containing bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) (Group-C). The buccal sides of Groups-B/-C were either sealed by fibrin sealant or by a biodegradable PLGA barrier membrane before soft-tissue closure. Computed tomography (CT), microCT and histology analyses were performed 12 weeks postoperatively. In vitro data demonstrated that BM-MSCs, with MSC properties confirmed, remained vital after integration with βTCP; and PLGA microspheres exhibited an initial burst followed by slow and continuous release of growth factors over a period of 28 days. In vivo data demonstrated that Group-B/-C sites had significantly greater gap obliteration, higher tissue mineral densities and more residual βTCP granules (p<0.05, Kruskal-Wallis tests). Qualitatively, Group-B/-C defect sites had started remodeling while Group-A sites were mainly forming new bone to bridge the gaps. Furthermore, βTCP degradation was not mediated by macrophages or osteoclasts, and was significantly slowed down by sealing the defects with barrier membrane. Combined, these data present a promising formulation composed of βTCP granules, autologous MSCs, controlled-release growth factors and biodegradable PLGA barrier membrane for the reconstruction of critical-size mandibular defects.

Effect of Mesenchymal Stem Cell Application on the Distracted Bone Microstructure: An Experimental Study

PURPOSE

Distraction osteogenesis (DO) is a surgical technique used to regenerate bone. The aim of this study was to improve bone quality and quantity during DO by the addition of mesenchymal stem cells (MSCs).

MATERIALS AND METHODS

The study was conducted on 12 goats assigned to a study group or a control group. In the study group, DO was aided with MSCs. Bone quality was assessed using energy dispersive x-ray (EDX), a scanning electron microscope (SEM), and histology. The histologic assessment was performed by measuring trabecular bone (TB) thickness in sections stained with hematoxylin and eosin (H&E) and by measuring osteoid bone percentage in sections stained with Masson trichrome (MT).

RESULTS

EDX showed an increase in calcification in the study group (mean Ca(2+), 17.58%; standard deviation [SD], 4.9%) compared with the control group (mean Ca(2+), 14.17%; SD, 6.7%). However, the increase was not statistically significant (P = .3354). Histomorphometric analysis of the H&E samples showed an increase in TB size in the study group (mean TB, 174.7 μm; SD, 33.5 μm) compared with the control group (mean TB, 115.4 μm; SD, 19.6 μm), and the increase was highly statistically significant (P = .0039). Analysis of the MT samples showed a decrease in osteoid percentage (mean osteoid percentage, 13.4%; SD, 2%) in the study group compared with the control group (mean osteoid percentage, 27.3%; SD, 3.5%). The decrease in osteoid percentage was statistically significant (P = .0001), indicating more rapid healing in the study group compared with the control group.

CONCLUSION

MSCs improved the bone quality of distracted bone and increased the crystal density in SEM images of the study group compared with that of the control group. MSCs showed promising results in improving the quality and quantity of distracted bone.

Growth characteristics underlying the lack of a chin in pigs: a histomorphometric study

OBJECTIVES

Despite similar mandibular growth to that of humans, pigs lack a chin projection as shown in most humans. To understand whether this divergence is contributed to differences in local symphyseal growth, this project characterized bone modeling activities at the symphyseal surfaces of juvenile pigs.

MATERIAL AND METHODS

Symphyseal specimens from two age groups (4- and 6-month-old, n = 10) were processed into histological sections with and without decalcification, which were assessed for surface mineral apposition and bone resorption, respectively. In a blinded fashion, measurements of four parameters (MAR: mineral apposition rate, MAZ: mineral apposition zone, ES/BS: eroded surface and OC.N/BS: osteoclast number) were obtained and tested by a multivariate two-way mixed-model analyses of variance (manova) for the differences between symphyseal regions and ages.

RESULTS

Qualitatively, pig symphyseal labial and lingual surfaces were horizontally oriented and characterized by mineral apposition and bone resorption, respectively. Quantitatively, labial mineral apposition tended to be greater rostrally than caudally at 4 months, which became greater caudally than rostrally at 6 months (region/age interactions: p = 0.127 for MAR, p = 0.012 for MAZ). Lingual bone resorption tended to be greater caudally than rostrally, but only ES/BS measurements were significant (p = 0.039) regardless of age, while OC.N/BS measurements varied with ages and regions (age/region interaction, p = 0.087).

CONCLUSIONS

Insufficient differential in symphyseal surface modeling between the labial-caudal and labial-rostral regions contributes to the lack of chin projection in the pig.

Scaffold-based delivery of adipose tissue-derived stem cells in rat frozen-thawed ovarian autografts: preliminary studies in a rat model

PURPOSE

This study aimed to evaluate whether a gelatin-based Gelfoam sponge is feasible as a scaffold for adipose tissue-derived stem cell (ASC) therapy in rat frozen-thawed ovarian autografts.

METHODS

Two sets of studies were performed. The in vitro set evaluated ASCs' viability in the Gelfoam scaffold at different times of co-culturing (after 24, 48, 72, 96, and 120 h). The in vivo set used 20 12-week-old adult female Wistar rats. Frozen-thawed ovarian grafts were treated with ASCs delivered in Gelfoam scaffolds immediately after an autologous retroperitoneal transplant (ASCs-GS, n = 10). The controls received Gelfoam with a culture medium (GS, n = 10). Assessment of graft quality was conducted by vaginal smears (until euthanasia on the 30th postoperative day), histological analyses, follicular density, and viability and fibrosis. Immunohistochemical staining for VEGF-A expression, vascular network (vWF), apoptosis (caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)), cell proliferation (Ki-67), and hormone receptors (estrogen and progesterone) were performed.

RESULTS

The cells remained viable in Gelfoam for up to 120 h of co-culturing. The graft morphology was similar among the groups. ASC therapy promoted the earlier resumption of the estrous phase (GS 16.6 ± 3 vs. ASCs-GS 12.8 ± 1.3 days) and enhanced estrogen receptors compared with the controls (p < 0.05) without interfering with the quantity and viability of the ovarian follicles, fibrosis, endothelial cells, VEGF immunoexpression, apoptosis, or cell proliferation (p > 0.05).

CONCLUSION

The Gelfoam scaffold could be a feasible and safe non-invasive technique for ASC delivery in the treatment of frozen-thawed ovarian autografts. Future studies should evaluate the real benefit of this treatment on the survival and endocrine activity of the graft.

Characterization of Insulin-Secreting Porcine Bone Marrow Stromal Cells Ex Vivo and Autologous Cell Therapy in Vivo

Cell therapy could potentially meet the need for pancreas and islet transplantations in diabetes mellitus that far exceeds the number of available donors. Bone marrow stromal cells are widely used in clinical trials mainly for their immunomodulatory effects with a record of safety. However, less focus has been paid to developing these cells for insulin secretion by transfection. Although murine models of diabetes have been extensively used in gene and cell therapy research, few studies have shown efficacy in large preclinical animal models. Here we report optimized conditions for ex vivo expansion and characterization of porcine bone marrow stromal cells and their permissive expression of a transfected insulin gene. Our data show that these cells resemble human bone marrow stromal cells in surface antigen expression, are homogeneous, and can be reproducibly isolated from outbred Yorkshire–Landrace pigs. Porcine bone marrow stromal cells were efficiently expanded in vitro to >1010 cells from 20 ml of bone marrow and remained karyotypically normal during expansion. These cells were electroporated with an insulin expression plasmid vector with high efficiency and viability, and secreted human insulin and C-peptide indicating appropriate processing of proinsulin. We showed that autologous insulin-secreting bone marrow stromal cells implanted and engrafted in the liver of a streptozotocin-diabetic pig that modeled type 1 diabetes resulted in partial, but significant, improvement in hyperglycemia that could not be ascribed to regeneration of endogenous β-cells. Glucose-stimulated insulin secretion in vivo from implanted cells in the treated pig was documented by a rise in serum human C-peptide levels during intravenous glucose tolerance tests. Compared to a sham-treated control pig, this resulted in significantly reduced fasting hyperglycemia, a slower rise in serum fructosamine, and prevented weight loss. Taken together, this study suggests that bone marrow stromal cells merit further development as autologous cell therapy for diabetes.

Bone Regeneration Is Promoted by Orally Administered Bovine Lactoferrin in a Rabbit Tibial Distraction Osteogenesis Model

BACKGROUND

Lactoferrin, an iron-binding glycoprotein which belongs to the transferrin family, has been shown to promote bone growth. However, reports regarding effects of lactoferrin on bone regeneration during distraction osteogenesis are limited. Our study was designed to investigate the effect of bovine lactoferrin treatment on bone formation of the distracted callus.

QUESTIONS/PURPOSES

We asked whether bovine lactoferrin enhances bone formation of the distraction callus as determined by (1) radiographic and histologic appearances; (2) dual-energy x-ray absorptiometry (DXA) analysis of bone mineral composition and bone mineral density; (3) micro-CT measures of trabecular architecture; and (4) biomechanical strength of the healing bone. Additionally, serology, reverse transcription (RT)-PCR, and immunohistochemistry were used to explore the possible mechanisms of bovine lactoferrin use on bone formation during distraction osteogenesis.

METHODS

Unilateral tibial osteodistraction was performed on 80 New Zealand White rabbits with a distraction rate of 1 mm per day for 10 days. Animals then were divided randomly into two groups: (1) vehicle and (2) bovine lactoferrin. At 4 and 8 weeks after completion of distraction, the animals were sacrificed. Lengthened tibias and serum samples were obtained and subjected to radiologic, DXA, micro-CT, histologic, and biomechanical examinations, and serum, RT-PCR and immunohistochemical analyses.

RESULTS

Radiologic, DXA, micro-CT, histologic, and biomechanical examinations indicated that bovine lactoferrin treatment not only accelerated bone formation at early stages of distraction osteogenesis but also promoted bone consolidation at late stages. The ultimate force of the distracted calluses was increased by 37% (118.8 ± 6.65 N in the lactoferrin group and 86.5 ± 5.47 N in the vehicle group; p < 0.001) and 84% (384.8 ± 18.4 N in the lactoferrin group and 209.0 ± 15.2 N in the vehicle group; p < 0.001) at 4 and 8 weeks, respectively. Moreover, serum analysis showed that bovine lactoferrin treatment significantly increased serum levels of bone alkaline phosphatase and decreased serum levels of tartrate resistant acid phosphatase 5b. In addition, RT-PCR and immunohistochemical analyses suggested that bovine lactoferrin treatment induced a lower receptor activator of nuclear factor-kappaB (RANK) ligand/osteoprotegerin (RANKL/OPG) ratio in the distracted callus.

CONCLUSIONS

The results of our study suggest that bovine lactoferrin treatment could promote bone regeneration during distraction osteogenesis in the rabbit. The results indicate that the OPG/RANKL/RANK system might be a major mechanism for increased bone formation and decreased bone resorption in distraction osteogenesis with bovine lactoferrin treatment.

CLINICAL RELEVANCE

Oral administration of bovine lactoferrin may provide a feasible approach for promoting osteogenesis during distraction osteogenesis.

Impact of surgical innovation on tissue repair in the surgical patient

BACKGROUND

Throughout history, surgeons have been prolific innovators, which is hardly surprising as most surgeons innovate daily, tailoring their intervention to the intrinsic uniqueness of each operation, each patient and each disease. Innovation can be defined as the application of better solutions that meet new requirements, unarticulated needs or existing market needs. In the past two decades, surgical innovation has significantly improved patient outcomes, complication rates and length of hospital stay. There is one key area that has great potential to change the face of surgical practice and which is still in its infancy: the realm of regenerative medicine and tissue engineering.

METHODS

A literature review was performed using PubMed; peer-reviewed publications were screened for relevance in order to identify key surgical innovations influencing regenerative medicine, with a focus on osseous, cutaneous and soft tissue reconstruction.

RESULTS

This review describes recent advances in regenerative medicine, documenting key innovations in osseous, cutaneous and soft tissue regeneration that have brought regenerative medicine to the forefront of the surgical imagination.

CONCLUSION

Surgical innovation in the emerging field of regenerative medicine has the ability to make a major impact on surgery on a daily basis.

Adipose tissue-derived stem cell therapy in rat cryopreserved ovarian grafts

The preliminary results of ovarian transplantation in clinical practice are encouraging. However, the follicular depletion caused by ischemic injury is a main concern and is directly related to short-term graft survival. Cell therapy with adipose tissue-derived stem cells (ASCs) could be an alternative to induce early angiogenesis in the graft. This study aimed to evaluate ASCs therapy in rat cryopreserved ovarian grafts. A single dose of rat ASC (rASCs) or vehicle was injected into the bilateral cryopreserved ovaries of twelve adult female rats immediately after an autologous transplant. Daily vaginal smears were performed for estrous cycle evaluation until euthanasia on postoperative day 30. Follicle viability, graft morphology and apoptosis were assessed. No differences were found with respect to estrous cycle resumption and follicle viability (P > 0.05). However, compared with the vehicle-treated grafts, the morphology of the ASCs-treated grafts was impaired, with diffuse atrophy and increased apoptosis (P < 0.05). ASCs direct injected in the stroma of rat cryopreserved ovarian grafts impaired its morphology although may not interfere with the functional resumption on short-term. Further investigations are necessary to evaluated whether it could compromise their viability in the long-term.

Association of mesenchymal stem cells and osteoblasts for bone repair

Aim: We tested the hypothesis that the association of bone marrow mesenchymal stem cells (MSCs) and osteoblasts (OBs) optimize bone repair. Materials & Methods: MSCs were cultured in growth or osteogenic medium and seeded into gelatin sponge prior to implantation. Defects were created into rat calvariae and implanted with gelatin sponge without cells, with MSCs, with OBs and with association of MSCs and OBs. Histological analysis and micro-CT-based histomorphometry were carried out after 4 weeks. Results: Increased bone formation was observed in defects treated with cells and bone volume was greater in defects treated with either OBs or MSCs/OBs. Conclusion: Association of MSCs and OBs did not increase the process of bone repair compared with cell-based therapy using either MSCs or OBs alone.