Use of fluorescence labeled mesenchymal stem cells in pluronic F127 and porous hydroxyapatite as a bone substitute for posterolateral spinal fusion

Bioengineered mesenchymal stem cell-derived exosomes: emerging strategies for diabetic wound healing

Diabetic wounds are among the most common complications of diabetes mellitus and their healing process can be delayed due to persistent inflammatory reactions, bacterial infections, damaged vascularization and impaired cell proliferation, which casts a blight on patients'health and quality of life. Therefore, new strategies to accelerate diabetic wound healing are being positively explored. Exosomes derived from mesenchymal stem cells (MSC-Exos) can inherit the therapeutic and reparative abilities of stem cells and play a crucial role in diabetic wound healing. However, poor targeting, low concentrations of therapeutic molecules, easy removal from wounds and limited yield of MSC-Exos are challenging for clinical applications. Bioengineering techniques have recently gained attention for their ability to enhance the efficacy and yield of MSC-Exos. In this review, we summarise the role of MSC-Exos in diabetic wound healing and focus on three bioengineering strategies, namely, parental MSC-Exos engineering, direct MSC-Exos engineering and MSC-Exos combined with biomaterials. Furthermore, the application of bioengineered MSC-Exos in diabetic wound healing is reviewed. Finally, we discuss the future prospects of bioengineered MSC-Exos, providing new insights into the exploration of therapeutic strategies.

Pluronic F127 hydrogel-loaded extracellular vesicles from adipose-derived mesenchymal stem cells promote tracheal cartilage regeneration via SCNN1B delivery

Extracellular vesicles (EVs) derived from adipose-derived mesenchymal stem cells (AMSC-EVs) have been highlighted as a cell-free therapy due to their regenerative capability to enhance tissue and organ regeneration. Herein, we aimed to examine the mechanism of PF127-hydrogel@AMSC-EVs in promoting tracheal cartilage defect repair. Based on bioinformatics methods, SCNN1B was identified as a key gene for the osteogenic differentiation of AMSCs induced by AMSC-EVs. EVs were isolated from rat AMSCs and then loaded onto thermo-sensitive PF-127 hydrogel to develop PF127-hydrogel@AMSC-EVs. It was established that PF127-hydrogel@AMSC-EVs could effectively deliver SCNN1B into AMSCs, where SCNN1B promoted AMSC osteogenic differentiation. The promotive effect was evidenced by enhanced ALP activity, extracellular matrix mineralization, and expression of s-glycosaminoglycan, RUNX2, OCN, collagen II, PERK, and ATF4. Furthermore, the in vivo experiments revealed that PF127-hydrogel@AMSC-SCNN1B-EVs stimulated tracheal cartilage regeneration in rats through PERK/ATF4 signaling axis activation. Therefore, PF127-hydrogel@AMSC-SCNN1B-EVs may be a novel cell-free biomaterial to facilitate tracheal cartilage regeneration and cartilage injury repair.

Hydrogels containing KYNA promote angiogenesis and inhibit inflammation to improve the survival rate of multi-territory perforator flaps

BACKGROUND

A new spray adhesive (KYNA-PF127) was established through the combination of thermosensitive hydrogel (Pluronic F127) and KYNA, aimed to investigate the effect of KYNA-PF127 on multi-territory perforator flaps and its possible molecular mechanism.

MATERIALS AND METHODS

36 SD male rats with 250-300 g were randomly divided into 3 groups (n = 12): control group, blank glue group and KYNA-PF127 group. KYNA-PF127 hydrogel was prepared and characterized for its morphology and properties using scanning electron microscopy. CCK-8 assay, scratch wound assay, transwell assay, tube formation assay and Ki67 staining were used to study the effect of KYNA-PF127 on the proliferation, migration, and tube formation of HUVECs. VEGF and FGF2 were measured by qPCR to evaluate the angiogenesis capacity of HUVECs in vitro. In vivo, the effect of each group on the survival area of the cross-zone perforator flap was evaluated, and angiogenesis was evaluated by HE and immunofluorescence (CD31 and MMP-9). The effect of inflammation on skin collagen fibers was assessed by Masson. Immunohistochemistry (SOD1, IL-1β, TNF-α) was used to evaluate the effects of oxidative stress and inflammatory factors on multi-territory flaps.

RESULTS

KYNA-PF127 has good sustained release and biocompatibility at 25% concentration. KYNA-PF127 promoted the proliferation, migration, and angiogenesis of HUVECs in vitro. In vivo, the survival area of multi-territory perforator flaps and angiogenic capability have increased after KYNA-PF127 intervention. KYNA-PF127 could effectively reduce the oxidative stress and inflammation of multi-territory perforator flaps.

CONCLUSION

KYNA-PF127 promotes angiogenesis through its antioxidant stress and anti-inflammatory effects, and shows potential clinical value in promoting the survival viability and drug delivery of multi-territory perforator flaps.

Thermosensitive hydrogel coupled with sodium ascorbyl phosphate promotes human umbilical cord-derived mesenchymal stem cell-mediated skin wound healing in mice

Poor survival and restricted function of transplanted stem cells are regarded as limiting their efficacy in wound recovery greatly. Consequently, it is necessary to identify innovative therapeutic strategies to solve these issues. Firstly, the biological effect of PF-127 hydrogel alone and in combination with SAP on the survival, and migration of cultured HUCMSCs was assessed by cell viability, apoptosis, and scratch wound assays. S. aureus and E. coli were used to evaluate the antibacterial activity of PF-127 plus SAP combination. Further, the ability of HUCMSCs-conditioned medium (HUCMSCs-CM) to promote the angiogenesis and migration of human umbilical vein endothelial cells (HUVECs) in vitro was evaluated using tube formation and transwell migration assays. Finally, the HUCMSCs embedded in PF-127 plus SAP scaffold were administered onto mice's excisional cutaneous wound bed. Histological and immunohistochemical analyses were employed to investigate the wound healing capacity as well as cellular responses of PF-127/HUCMSCs/SAP hydrogel. PF-127 showed cytotoxicity on HUCMSCs, whereas the addition of SAP significantly promoted cell viability and alleviated apoptosis of HUCMSCs encapsulated in PF-127 hydrogel in vitro. SAP supplementation substantially abrogated the inhibiting effect of PF-127 on the migration of HUCMSCs in vitro. The combination of PF-127 and SAP exerted an obvious bacteriostatic function on S. aureus and E. coli. Moreover, the co-treatment with SAP could remarkably enhance the stimulative effect of HUCMSCs-CM on the angiogenesis and migration of HUVECs in vitro. PF-127 combined SAP-embedded HUCMSCs transplantation resulted in a potently accelerated wound healing process, promoted the number of proliferating cells and newly formed blood vessels, as well as enhanced expression of vascular endothelial growth factor. PF-127 coupled with SAP contributes to HUCMSCs-mediated traumatic wound closure in mice by promoting cell survival, antibacterial action, and angiogenesis. Our results offered a theoretical foundation for the clinical treatment of traumatic skin defects.

Mechanisms of action underlying the effect of Tongsaimai on wound healing based on experimental and network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Tongsaimai (TSM) is a traditional Chinese medicine that has several therapeutic qualities, including anti-inflammatory, anti-oxidative, and anti-vasculitis effects. However, its impacts and underlying mechanisms on wound healing remain unclear.

AIM OF THE STUDY

The aim of our study was to evaluate TSM for its pro-healing effect and the relevant mechanisms using both experimental validation and network pharmacology analysis.

MATERIALS AND METHODS

The components of TSM were detected by high-performance liquid chromatography combined with diode array detector (HPLC-DAD). Skin wounds with a diameter of 4 mm were created on the backs of mice, after which, topical treatments of 2.5-10% TSM were applied onto the lesions once daily for either 2 or 7 days. Then, the wound tissues were collected to determine the impacts of TSM on collagen deposition, epithelial cell proliferation, oxidative stress, inflammation, and angiogenesis. Moreover, the effects of TSM (0.5-2 mg/mL) on the cell viability of HUVECs and HaCaT cells were evaluated.

RESULTS

A total of 11 components in TSM were identified by HPLC-DAD. TSM was found to enhance the rate of wound contraction and increase epithelial thickness and collagen deposition during the healing process. In addition, TSM increased SOD activity and downregulated MDA and IL-1β levels in the wound tissues. Immunofluorescence analysis further indicated an increased expression of Ki67, CD31, and VEGF in wound tissues following TSM administration. Results of the network pharmacology analysis revealed that multiple pathways including VEGF, PI3K/Akt, and MAPK pathways were involved in the pharmacological actions of TSM on wound healing. Accordantly, in vitro experiments revealed that TSM promoted the proliferation of HUVECs and HaCaT cells while activating the PI3K/Akt pathway.

CONCLUSIONS

Our results suggest that TSM may serve as a therapeutic medication to improve wound healing by employing multiple regulatory mechanisms that affect proliferation, angiogenesis, collagen deposition, oxidative stress, and inflammation.

Human Umbilical Cord Mesenchymal Stem Cells Encapsulated with Pluronic F-127 Enhance the Regeneration and Angiogenesis of Thin Endometrium in Rat via Local IL-1β Stimulation

Thin endometrium (< 7 mm) could cause low clinical pregnancy, reduced live birth, increased spontaneous abortion, and decreased birth weight. However, the treatments for thin endometrium have not been well developed. In this study, we aim to determine the role of Pluronic F-127 (PF-127) encapsulation of human umbilical cord mesenchymal stem cells (hUC-MSCs) in the regeneration of thin endometrium and its underlying mechanism. Thin endometrium rat model was created by infusion of 95% ethanol. Thin endometrium modeled rat uterus were treated with saline, hUC-MSCs, PF-127, or hUC-MSCs plus PF-127 separately. Regenerated rat uterus was measured for gene expression levels of angiogenesis factors and histological morphology. Angiogenesis capacity of interleukin-1 beta (IL-1β)-primed hUC-MSCs was monitored via quantitative polymerase chain reaction (q-PCR), Luminex assay, and tube formation assay. Decreased endometrium thickness and gland number and increased inflammatory factor IL-1β were achieved in the thin endometrium rat model. Embedding of hUC-MSCs with PF-127 could prolong the hUC-MSCs retaining, which could further enhance endometrium thickness and gland number in the thin endometrium rat model via increasing angiogenesis capacity. Conditional medium derived from IL-1β-primed hUC-MSCs increased the concentration of angiogenesis factors (basic fibroblast growth factor (bFGF), vascular endothelial growth factors (VEGF), and hepatocyte growth factor (HGF)). Improvement in the thickness, number of glands, and newly generated blood vessels could be achieved by uterus endometrium treatment with PF-127 and hUC-MSCs transplantation. Local IL-1β stimulation-primed hUC-MSCs promoted the release of angiogenesis factors and may play a vital role on thin endometrium regeneration.

Combination Therapy of Stem Cell-derived Exosomes and Biomaterials in the Wound Healing

Wound healing is a serious obstacle due to the complexity of evaluation and management. While novel approaches to promoting chronic wound healing are of critical interest at the moment, several studies have demonstrated that combination therapy is critical for the treatment of a variety of diseases, particularly chronic wounds. Among the various approaches that have been proposed for wound care, regenerative medicine-based methods have garnered the most attention. As is well known, regenerative medicine's three primary tools are gene/cell therapy, biomaterials, and tissue engineering. Multifunctional biomaterials composed of synthetic and natural components are highly advantageous for exosome carriers, which utilizing them is an exciting wound healing method. Recently, stem cell-secreted exosomes and certain biomaterials have been identified as critical components of the wound healing process, and their combination therapy appears to produce significant results. This paper presents a review of literature and perspectives on the use of stem cell-derived exosomes and biomaterials in wound healing, particularly chronic wounds, and discusses the possibility of future clinical applications.

Randomized clinical trial: expanded autologous bone marrow mesenchymal cells combined with allogeneic bone tissue, compared with autologous iliac crest graft in lumbar fusion surgery

BACKGROUND CONTEXT

Although autogenous iliac crest bone graft (AICBG) is considered the gold-standard graft material for spinal fusion, new bone substitutes are being developed to avoid associated complications and disadvantages. By combining autologous bone marrow mesenchymal stromal cells (MSCs) expanded ex vivo and allogenic cancellous bone graft, we obtain a tissue-engineered product that is osteoconductive and potentially more osteogenic and osteoinductive than AICBG, owing to the higher concentration of MSCs.

PURPOSE

This study aimed to evaluate the feasibility and safety of implanting a tissue-engineered product consisting of expanded bone marrow MSCs loaded onto allograft bone (MSC+allograft) for spinal fusion in degenerative spine disease, as well as to assess its clinical and radiological efficacy.

STUDY DESIGN/SETTING

A prospective, multicenter, open-label, blinded-reader, randomized, parallel, single-dose phase I-II clinical trial.

PATIENT SAMPLE

A total of 73 adult patients from 5 hospitals, with Meyerding grade I-II L4-L5 degenerative spondylolisthesis and/or with L4-L5 degenerative disc disease who underwent spinal fusion through transforaminal lumbar interbody fusion (TLIF).

OUTCOME MEASURES

Spinal fusion was assessed by plain X-ray at 3, 6, and 12 months and by computed tomography (CT) at 6 and 12 months post-treatment. An independent radiologist performed blinded assessments of all images. Clinical outcomes were measured as change from baseline value: visual analog scale for lumbar and sciatic pain at 12 days, 3, 6, and 12 months posttreatment, and Oswestry Disability Index and Short Form-36 at 3, 6, and 12 months posttreatment.

METHODS

Patients who underwent L4-L5 TLIF were randomized for posterior graft type only, and received either MSC+allograft (the tissue-engineered product, group A) or AICBG (standard graft material, group B). Standard graft material was used for anterior fusion in all patients. Feasibility was measured primarily as the percentage of randomized patients who underwent surgery in each treatment group. Safety was assessed by analyzing treatment-emergent adverse events (AEs) for the full experimental phase and appraising their relationship to the experimental treatment. Outcome measures, both radiological and clinical, were compared between the groups.

RESULTS

Seventy-three patients were randomized in this study, 36 from the MSC+allograft group and 37 from the AICBG group, and 65 were surgically treated (31 group A, 34 group B). Demographic and comorbidity data showed no difference between groups. Most patients were diagnosed with grade I or II degenerative spondylolisthesis. MSC+allograft was successfully implanted in 86.1% of randomized group A patients. Most patients suffered treatment-emergent AEs during the study (88.2% in group A and 97.1% in group B), none related to the experimental treatment. X-ray-based rates of posterior spinal fusion were significantly higher for the experimental group at 6 months (p=.012) and 12 months (p=.0003). CT-based posterior fusion rates were significantly higher for MSC+allograft at 6 months (92.3% vs 45.7%; p=.0001) and higher, but not significantly, at 12 months (76.5% vs 65.7%; p=.073). CT-based complete response (defined as the presence of both posterior intertransverse fusion and anterior interbody fusion) was significantly higher at 6 months for MSC+allograft than for AICBG (70.6% vs 40%; p=.0038), and remained so at 12 months (70.6% vs 51.4%; p=.023). Clinical results including patient-reported outcomes improved postsurgery, although there were no differences between groups.

CONCLUSIONS

Compared with the current gold standard, our experimental treatment achieved a higher rate of posterior spinal fusion and radiographic complete response to treatment at 6 and 12 months after surgery. The treatment clearly improved patient quality of life and decreased pain and disability at rates similar to those for the control arm. The safety profile of the tissue-engineered product was also similar to that for the standard material, and no AEs were linked to the product. Procedural AEs did not increase as a result of BM aspiration. The use of expanded bone marrow MSCs combined with cancellous allograft is a feasible and effective technique for spinal fusion, with no product-related AEs found in our study.

Umbilical Cord-Derived Mesenchymal Stem Cell-Derived Exosomes Combined Pluronic F127 Hydrogel Promote Chronic Diabetic Wound Healing and Complete Skin Regeneration

Purpose

Chronic refractory wounds are a multifactorial comorbidity of diabetes mellitus with the characteristic of impaired vascular networks. Currently, there is a lack of effective treatments for such wounds. Various types of mesenchymal stem cell-derived exosomes (MSC-exos) have been shown to exert multiple therapeutic effects on skin regeneration. We aimed to determine whether a constructed combination of human umbilical cord MSC (hUCMSC)-derived exosomes (hUCMSC-exos) and Pluronic F-127 (PF-127) hydrogel could improve wound healing.

Materials and Methods

We topically applied human umbilical cord-derived MSC (hUCMSC)-derived exosomes (hUCMSC-exos) encapsulated in a thermosensitive PF-127 hydrogel to a full-thickness cutaneous wound in a streptozotocin-induced diabetic rat model. The material properties and wound healing ability of the hydrogel and cellular responses were analyzed.

Results

Compared with hUCMSC-exos, PF-127-only or control treatment, the combination of PF-127 and hUCMSC-exos resulted in a significantly accelerated wound closure rate, increased expression of CD31 and Ki67, enhanced regeneration of granulation tissue and upregulated expression of vascular endothelial growth factor (VEGF) and factor transforming growth factor beta-1 (TGFβ-1).

Conclusion

The efficient delivery of hUCMSC-exos in PF-127 gel and improved exosome ability could promote diabetic wound healing. Thus, this biomaterial-based exosome therapy may represent a new therapeutic approach for cutaneous regeneration of chronic wounds.

PF-127 hydrogel plus sodium ascorbyl phosphate improves Wharton's jelly mesenchymal stem cell-mediated skin wound healing in mice

Background

Factors such as poor engraftment, retention, and survival of the transplanted stem cells are deemed to limit their therapeutic efficacy for wound regeneration. Hence, it is necessary to explore these issues in order to resolve them. In this study, we aim to investigate the role of Pluronic F-127 (PF-127) hydrogel plus antioxidant sodium ascorbyl phosphate (SAP) in enhancing Wharton’s jelly mesenchymal stem cell (WJMSC)-mediated effectiveness on full-thickness skin wound healing in mice.

Methods

First, the cytotoxicity of PF-127 and the biological effect of SAP on the survival of WJMSCs were tested in vitro using cell viability and proliferation assays. Next, a cell suspension containing WJMSCs, PF-127, and SAP was topically administered onto an 8-mm diameter excisional full-thickness wound bed. Eight days after transplantation, the mice were sacrificed and the skin tissue was excised for histological and immunohistochemical analysis. Finally, in vivo distribution of transplanted WJMSCs was traced to investigate cell engraftment and the potential therapeutic mechanism.

Results

PF-127 was found to be cytotoxic to WJMSCs while SAP significantly improved the survival of PF-127-embedded WJMSCs. When this combination was topically transplanted onto the wound bed, wound healing was facilitated and dermis regeneration was achieved on the 8th day after surgery, as evidenced by an increase in dermal thickness, newly developed hair follicles, and collagen fiber deposition accompanied by a reduction in scar width. Further, immunohistochemical analysis demonstrated a higher number of anti-inflammatory M2 macrophages, proliferating cells, and newly formed blood vessels in the WJMSCs/PF-127/SAP group relative to all other groups. In addition, in vivo tracking results revealed a highly enhanced engraftment of WJMSCs accumulated in the dermis in the WJMSCs/PF-127/SAP group.

Conclusions

SAP significantly improves the survival of WJMSCs in PF-127 encapsulation. Further, PF-127 plus SAP is an effective combination that enhances WJMSC engraftment in the dermis, which then promotes full-thickness wound healing through potential M2 macrophage formation and angiogenesis.

Influence of magnesium particles and Pluronic F127 on compressive strength and cytocompatibility of nanocomposite injectable and moldable beads for bone regeneration

A novel one-step preparation of magnesium particles and Pluronic F127 incorporated with calcium sulfate hemihydrate (CSH) and nano-hydroxyapatite (nHA) ready to use injectable or moldable beads was developed for bone tissue regeneration applications. The nanocomposite showed setting time less than 15 min, very good injectability (75-85%) and good mechanical strength (52-80 MPa). Samples immersed in SBF showed controlled degradation (40-45% reduction in weight) in 28 days. The nanocomposite bone graft was cytocompatible against MG63 osteosarcoma cells and increased the osteogenic gene expression by 2-3 folds. These results indicate that it can be a potential defect filling biomaterial for bone tissue regeneration at the fracture site.

In situ formation of interpenetrating polymer network using sequential thermal and click crosslinking for enhanced retention of transplanted cells

Injectable hydrogels, which are used as scaffolds in cell therapy, provide a minimally invasive strategy to enhance cell retention and survival at injection site. However, till now, slow in situ gelation, undesired mechanical properties, and weak cell adhesion characteristics of reported hydrogels, have led to improper results. Here, we developed an injectable fully-interpenetrated polymer network (f-IPN) by integration of Diels-Alder (DA) crosslinked network and thermosensitive injectable hydrogel. The proposed DA hydrogels were formed in a slow manner showing robust mechanical properties. Interpenetration of thermosensitive network into DA hydrogel accelerated in situ gel-formation and masked the slow reaction rate of DA crosslinking while keeping its unique features. Two networks were formed by simple syringe injection without the need of any initiator, catalyst, or double barrel syringe. The DA and f-IPN hydrogels showed comparable viscoelastic properties along with outstanding load-bearing and shape-recovery even under high levels of compression. The subcutaneous administration of cardiomyocytes-laden f-IPN hydrogel into nude mice revealed high cell retention and survival after two weeks. Additionally, the cardiomyocyte's identity of retained cells was confirmed by detection of human and cardiac-related markers. Our results indicate that the thermosensitive-covalent networks can open a new horizon within the injection-based cell therapy applications.

Mesenchymal Stem Cells for the Treatment of Spinal Arthrodesis: From Preclinical Research to Clinical Scenario

The use of spinal fusion procedures has rapidly augmented over the last decades and although autogenous bone graft is the “gold standard” for these procedures, alternatives to its use have been investigated over many years. A number of emerging strategies as well as tissue engineering with mesenchymal stem cells (MSCs) have been planned to enhance spinal fusion rate. This descriptive systematic literature review summarizes the in vivo studies, dealing with the use of MSCs in spinal arthrodesis surgery and the state of the art in clinical applications. The review has yielded promising evidence supporting the use of MSCs as a cell-based therapy in spinal fusion procedures, thus representing a suitable biological approach able to reduce the high cost of osteoinductive factors as well as the high dose needed to induce bone formation. Nevertheless, despite the fact that MSCs therapy is an interesting and important opportunity of research, in this review it was detected that there are still doubts about the optimal cell concentration and delivery method as well as the ideal implantation techniques and the type of scaffolds for cell delivery. Thus, further inquiry is necessary to carefully evaluate the clinical safety and efficacy of MSCs use in spine fusion.

Cartilage repair by human umbilical cord blood-derived mesenchymal stem cells with different hydrogels in a rat model

This study was carried out to assess the feasibility of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in articular cartilage repair and to further determine a suitable delivering hydrogel in a rat model. Critical sized full thickness cartilage defects were created. The hUCB-MSCs and three different hydrogel composites (hydrogel A; 4% hyaluronic acid/30% pluronic (1:1, v/v), hydrogel B; 4% hyaluronic acid, and hydrogel C; 4% hyaluronic acid/30% pluronic/chitosan (1:1:2, v/v)) were implanted into the experimental knee (right knee) and hydrogels without hUCB-MSCs were implanted into the control knee (left knee). Defects were evaluated after 8 weeks. The hUCB-MSCs with hydrogels composites resulted in a better repair as seen by gross and histological evaluation compared with hydrogels without hUCB-MSCs. Among the three different hydrogels, the 4% hyaluronic acid hydrogel composite (hydrogel B) showed the best result in cartilage repair as seen by the histological evaluation compared with the other hydrogel composites (hydrogel A and C). The results of this study suggest that hUCB-MSCs may be a promising cell source in combination with 4% hyaluronic acid hydrogels in the in vivo repair of cartilage defects.

Mouse bone marrow-derived mesenchymal stem cells inhibit leukemia/lymphoma cell proliferation in vitro and in a mouse model of allogeneic bone marrow transplant

The allogeneic hematopoietic stem cell (HSC) transplantation of mesenchymal stem cells (MSCs) contributes to the reconstitution of hematopoiesis by ameliorating acute graft‑versus‑host disease (aGVHD). However, the role of MSCs in graft‑versus‑leukemia remains to be determined. In the present study, we co‑cultured C57BL/6 mouse bone marrow (BM)‑derived MSCs with A20 murine B lymphoma, FBL3 murine erythroleukemia and P388 murine acute lymphocytic leukemia cells. Cell proliferation, apoptosis, cell cycle progression and the amount of cytokine secretion were then measured using a Cell Counting kit‑8, Annexin V/propidium iodide staining, flow cytometry and ELISA, respectively. We also established a model of allogeneic bone marrow transplantation (BMT) using BALB/c mice. Following the administration of A20 cells and MSCs, we recorded the symptoms and the survival of the mice for 4 weeks, assessed the T cell subsets present in peripheral blood, and, after the mice were sacrifice, we determined the infiltration of MSCs into the organs by histological staining. Our results revealed that the MSCs inhibited the proliferation of the mouse lymphoma and leukemia cells in vitro, leading to cell cycle arrest and reducing the secretion of interleukin (IL)‑10. In our model of allogeneic BMT, the intravenous injection of MSCs into the mice injected wth A20 cells decreased the incidence of lymphoma, improved survival, increased the fraction of CD3+CD8+ T cells, decreased the fraction of CD3+CD4+ T cells and CD4+CD25+ T cells in peripheral blood, and ameliorated the manifestation of aGVHD. The results from the present study indicate that MSCs may be safe and effective when used in allogeneic BMT for the treatment of hemotological malignancies.

Pluronic F-127 hydrogel as a promising scaffold for encapsulation of dental-derived mesenchymal stem cells

Dental-derived mesenchymal stem cells (MSCs) provide an advantageous therapeutic option for tissue engineering due to their high accessibility and bioavailability. However, delivering MSCs to defect sites while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated tissue regeneration. Here, we tested the osteogenic and adipogenic differentiation capacity of dental pulp stem cells (DPSCs) in a thermoreversible Pluronic F127 hydrogel scaffold encapsulation system in vitro. DPSCs were encapsulated in Pluronic (®) F-127 hydrogel and stem cell viability, proliferation and differentiation into adipogenic and osteogenic tissues were evaluated. The degradation profile and swelling kinetics of the hydrogel were also analyzed. Our results confirmed that Pluronic F-127 is a promising and non-toxic scaffold for encapsulation of DPSCs as well as control human bone marrow MSCs (hBMMSCs), yielding high stem cell viability and proliferation. Moreover, after 2 weeks of differentiation in vitro, DPSCs as well as hBMMSCs exhibited high levels of mRNA expression for osteogenic and adipogenic gene markers via PCR analysis. Our histochemical staining further confirmed the ability of Pluronic F-127 to direct the differentiation of these stem cells into osteogenic and adipogenic tissues. Furthermore, our results revealed that Pluronic F-127 has a dense tubular and reticular network morphology, which contributes to its high permeability and solubility, consistent with its high degradability in the tested conditions. Altogether, our findings demonstrate that Pluronic F-127 is a promising scaffold for encapsulation of DPSCs and can be considered for cell delivery purposes in tissue engineering.

Factors influencing arthrodesis rates in a rabbit posterolateral spine model with iliac crest autograft

PURPOSE

The rabbit posterolateral intertransverse spine arthrodesis model has been widely used to evaluate spinal biologics. However, to date, the validity and reproducibility of performance of iliac crest bone graft, the most common and critical control group, has not been firmly established. We evaluated original research publications that utilized this model, identified which experimental conditions affected fusion rates, and developed an algorithm to predict fusion rates for future study designs.

METHODS

A MEDLINE search was performed for publications through December, 2011 that utilized this model to evaluate fusion rates elicited by iliac crest autograft. All study parameters were recorded, and logistic regression analyses were performed to determine the effects of these variables on fusion rates as determined by either manual palpation or radiographs.

RESULTS

Seventy studies with 959 rabbits in 102 groups met the inclusion criteria. Excluding studies that measured fusion at 4 or fewer weeks or intentionally tried to decrease the fusion rate, the overall fusion rate for autograft was 58.3 ± 16.3 % (mean ± SD) as determined by manual palpation and 66.4 ± 17.8 % by plain radiographs. Regression analysis demonstrated a difference between these outcome measures with a trend towards significance (p = 0.09). Longer time points and larger volumes of autograft resulted in significantly greater reported fusion rates (p < 0.0001 and p < 0.05, respectively). Neither strain, age, weight, nor vertebral level significantly affected fusion rates.

CONCLUSIONS

Although experimental conditions varied across studies, time point evaluation and autograft volume significantly affected fusion rates. Despite some variability demonstrated across certain studies, we demonstrated that when the time point and volume of autograft were controlled for, the iliac crest control group of the rabbit posterolateral spinal arthrodesis model is both reliable and predictably affected by different experimental conditions.

Tissue engineering strategies in spinal arthrodesis: the clinical imperative and challenges to clinical translation

Skeletal disorders requiring the regeneration or de novo production of bone present considerable reconstructive challenges and are one of the main driving forces for the development of skeletal tissue engineering strategies. The skeletal or mesenchymal stem cell is a fundamental requirement for osteogenesis and plays a pivotal role in the design and application of these strategies. Research activity has focused on incorporating the biological role of the mesenchymal stem cell with the developing fields of material science and gene therapy in order to create a construct that is not only capable of inducing host osteoblasts to produce bone, but is also osteogenic in its own right. This review explores the clinical need for reparative approaches in spinal arthrodesis, identifying recent tissue engineering strategies employed to promote spinal fusion, and considers the ongoing challenges to successful clinical translation.

Comparison of autogenic and allogenic bone marrow derived mesenchymal stem cells for repair of segmental bone defects in rabbits

Autogenic and allogenic bone marrow derived mesenchymal stem cells (BM-MSCs) were compared for repair of bone gap defect in rabbits. BM-MSCs were isolated from bone marrow aspirates and cultured in vitro for allogenic and autogenic transplantation. A 5mm segmental defect was created in mid-diaphysis of the radius bone. The defect was filled with hydroxyapatite alone, hydroxyapatite with autogeneic BM-MSCs and hydroxyapatite with allogenic BM-MSCs in groups A, B and C, respectively. On an average 3.45×10(6) cells were implanted at each defect site. Complete bridging of bone gap with newly formed bone was faster in both treatment groups as compared to control group. Histologically, increased osteogenesis, early and better reorganization of cancellous bone and more bone marrow formation were discernible in treatment groups as compared to control group. It was concluded that in vitro culture expanded allogenic and autogenic BM-MSCs induce similar, but faster and better healing as compared to control.

[Spinal arthrodesis. basic science]

Spinal arthrodesis consists of a combination of a system of mechanical stabilisation of one or more vertebral segments with a biological substance that promotes osteoneogenesis, with aim of achieving the permanent fusion between areas more or less the same size of these segments. In spinal arthrodesis, the biological support par excellence is the autograft. However, obtaining this involves a high incidence of morbidity and, in cases of arthrodesis of more than one intervertebral space, the quantity available is usually insufficient. The extraction and implantation time prolongs the surgery, increasing the exposure to and risk of bleeding and infection. For these reasons, there is a search for substances that possess the properties of the autograft, avoiding the morbidity and added surgical time required to extract the autograft. The biomechanical-biological interaction in vertebral arthrodesis has been studied in this article.

The use of fluorescence-labeled mesenchymal stem cells in poly(lactide-co-glycolide)/hydroxyapatite/collagen hybrid graft as a bone substitute for posterolateral spinal fusion

BACKGROUND

Posterolateral spinal fusion is used to treat patients with degenerative spinal disorders. In this study, we investigated the effectiveness of a mesenchymal stem cell (MSC)/hydroxyapatite/type I collagen hybrid graft for posterolateral spinal fusion in a rabbit model.

METHODS

In vitro study, the hybrid graft was cultured in complete or osteogenic medium for 7 days and 14 days and examined by scanning electron microscopy. The alkaline phosphatase activity of the MSCs was assessed and the expression of osteogenic gene was determined by reverse transcription polymerase chain reaction. In vivo investigation, spinal fusion was examined using radiography, manual palpation, computed tomography, torsional loading tests, and histologic analysis. Furthermore, using a PKH fluorescence labeling system, we examined whether the newly formed bone was derived from the transplanted MSCs.

RESULTS

Our data suggested that the MSCs differentiated into osteoblasts and produced extracellular matrix in the hybrid graft. Increased alkaline phosphatase activity was noted and mRNA of Cbfa-1 and osteopontin were detected. Radiographs and computed tomography images showed a continuous bone bridge and a satisfactory fusion mass incorporated into the transverse processes. The results of manual palpation and biomechanical data did not significantly differ between the two groups. Histologic examination of both groups revealed the presence of cartilage and endochondral ossification in the gaps between the grafted fragments. In situ tracing of the PKH 67-labeled MSCs indicated that the transplanted MSCs were partly responsible for the new bone formation.

CONCLUSION

The hybrid graft could be effectively used to achieve posterolateral spinal fusion.