Effect of platelet-rich plasma on dental stem cells derived from human impacted third molars

Recent Advances in Apical Periodontitis Treatment: A Narrative Review

Apical periodontitis is an inflammatory response caused by pulp infection. It induces bone resorption in the apical and periapical regions of the tooth. The most conservative approach to treat this condition is nonsurgical endodontic treatment. However, clinical failure has been reported with this approach; thus, alternative procedures are required. This review highlights recent literature regarding advanced approaches for the treatment of apical periodontitis. Various therapies, including biological medications, antioxidants, specialized pro-resolving lipid mediators, and stem cell therapy, have been tested to increase the success rate of treatment for apical periodontitis. Some of these approaches remain in the in vivo phase of research, while others have just entered the translational research phase to validate clinical application. However, a detailed understanding of the molecular mechanisms that occur during development of the immunoinflammatory reaction in apical periodontitis remains unclear. The aim of this review was to summarize advanced approaches for the treatment of apical periodontitis. Further research can confirm the potential of these alternative nonsurgical endodontic treatment approaches.

Effects of non-steroidal anti-inflammatory drug (ibuprofen) in low and high dose on stemness and biological characteristics of human dental pulp-derived mesenchymal stem cells

PURPOSE

The effect of ibuprofen, an NSAID, on biological characteristics such as proliferation, viability, DNA damage and cell cycle in dental pulp derived stem cells (DPSCs) can be important for regenerative medicine. Our aim is to investigate how low and high doses of ibuprofen affect stem cell characteristics in DPSCs.

MATERIALS AND METHODS

DPSCs were isolated from human teeth and characterized by flow cytometry and differentiation tests. Low dose (0.1 mmol/L) and high dose (3 mmol/L) ibuprofen were administered to DPSCs. Surface markers between groups were analyzed by immunofluorescence staining. Membrane depolarization, DNA damage, viability and cell cycle analysis were performed between groups using biological activity test kits. Cellular proliferation was measured by the MTT and cell count kit. Statistical analyzes were performed using GraphPad Prism software.

RESULTS

High dose ibuprofen significantly increased CD44 and CD73 expression in DPSCs. High-dose ibuprofen significantly reduced mitochondrial membrane depolarization in DPSCs. It was determined that DNA damage in DPSCs decreased significantly with high dose ibuprofen. Parallel to this, cell viability increased significantly in the ibuprofen applied groups. High-dose ibuprofen was found to increase mitotic activity in DPSCs. Proliferation in DPSCs increased in parallel with the increase in mitosis stage because of high-dose ibuprofen administration compared to the control and low-dose ibuprofen groups. Our proliferation findings appeared to support cell cycle analyses.

CONCLUSION

High dose ibuprofen improved the immunophenotypes and biological activities of DPSCs. The combination of ibuprofen in the use of DPSCs in regenerative medicine can make stem cell therapy more effective.

Biomimetic Approaches in Clinical Endodontics

In the last few decades, biomimetic concepts have been widely adopted in various biomedical fields, including clinical dentistry. Endodontics is an important sub-branch of dentistry which deals with the different conditions of pulp to prevent tooth loss. Traditionally, common procedures, namely pulp capping, root canal treatment, apexification, and apexigonesis, have been considered for the treatment of different pulp conditions using selected materials. However, clinically to regenerate dental pulp, tissue engineering has been advocated as a feasible approach. Currently, new trends are emerging in terms of regenerative endodontics which have led to the replacement of diseased and non-vital teeth into the functional and healthy dentine-pulp complex. Root- canal therapy is the standard management option when dental pulp is damaged irreversibly. This treatment modality involves soft-tissue removal and then filling that gap through the obturation technique with a synthetic material. The formation of tubular dentine and pulp-like tissue formation occurs when stem cells are transplanted into the root canal with an appropriate scaffold material. To sum up tissue engineering approach includes three components: (1) scaffold, (2) differentiation, growth, and factors, and (3) the recruitment of stem cells within the pulp or from the periapical region. The aim of this paper is to thoroughly review and discuss various pulp-regenerative approaches and materials used in regenerative endodontics which may highlight the current trends and future research prospects in this particular area.

Evaluation of the effect of autologous conditioned serum on the radiographic characteristics of hard tissue after horizontal bone augmentation in implant dentistry

Background. Bone deficiency in different areas is problematic in implant placement. Changes in histological, histomorphometric, and radiographic properties of hard tissues in the implant placement area affect many parameters of implant success. Autologous conditioned serum (ACS) is a blood product with high levels of IL1- receptor antagonists. Augmentation surgeries are required in many cases because implant placement in the edentulous areas requires a sufficient amount of bone. Therefore, this study radiographically evaluated the effect of autologous conditioned serum after horizontal bone augmentation. Methods. In this prospective RCT, 21 patients eligible patients were evaluated. The patient underwent horizontal ridge augmentation surgery in the area. The ACS-impregnated graft was in direct con-tact with the bone. The control side underwent the same surgical protocol without using ACS. Four months after surgery, a CBCT radiograph was taken, and radiographic changes in the two areas were calculated using the differences in the amount of bone formed in the horizontal dimension as well as the Hounsfield unit (HU). The data were reported using descriptive statistical methods, including means (standard deviations) and frequencies (percentages). According to the results of the Kolmog-orov-Smirnov test, the data had a normal distribution (P>0.05); therefore, paired t-test was used to compare the means of the parameters between the two groups. Results. IRadiographic examinations showed that the horizontal dimension of bone before surgery was similar between the two groups. However, after surgery in the ACS group (33.13±6.1), it was significantly higher than in the control group (62.1±86.4) (P>0.05). Also, the rate of horizontal dimension increase (the difference before and after surgery) in the ACS group was significantly higher than in the control group. Bone density before surgery was similar between the two groups. However, after surgery, there was a significant increase in the ACS group (75.56±330.42 HUs) compared to the control group (38.35±292.38 HUs) (P>0.05). Also, the rate of density increase (the difference before and after surgery) in the ACS group was significantly higher than in the control group. Conclusion. Radiographic evaluations of hard tissues showed a significant increase in the horizontal dimension of bone and density of newly formed bone using ACS compared to the control group.

Effect of Human Platelet Lysate as Cultivation Nutrient Supplement on Human Natal Dental Pulp Stem Cell In Vitro Expansion

Despite several scientific or ethical issues, fetal bovine serum (FBS) remains the standard nutrient supplement in the mesenchymal stem cell cultivation medium. Cell amplification plays an important role in human stem cell therapies. Increasing interest in this field has supported attempts to find suitable human alternatives to FBS for in vitro cell propagation. Human platelet lysate (hPL) has recently been determined as one of them. Our study aimed to evaluate the influence of 2% hPL in the growth medium for in vitro expansion of human natal dental pulp stem cells (hNDP-SCs). The effect was determined on proliferation rate, viability, phenotype profile, expression of several markers, relative telomere length change, and differentiation potential of four lineages of hNDP-SCs. As a control, hNDP-SCs were simultaneously cultivated in 2% FBS. hNDP-SCs cultivated in hPL showed a statistically significantly higher proliferation rate in initial passages. We did not observe a statistically significant effect on mesenchymal stem cell marker (CD29, CD44, CD73, CD90) or stromal-associated marker (CD13, CD166) expression. The cell viability, relative telomere length, or multipotency remained unaffected in hNDP-SCs cultivated in hPL-medium. In conclusion, hPL produced under controlled and standardized conditions is an efficient serum supplement for in vitro expansion of hNDP-SCs.

Transforming growth factor β1-enriched secretome up-regulate osteogenic differentiation of dental pulp stem cells, and a potential therapeutic for gingival wound healing: A comparative proteomics study

OBJECTIVES

Current study aimed at comparing the human dental pulp-derived stem cell (hDPSC) secretome (Control secretome) and transforming growth factor beta1 (TGF-β1)-transfected hDPSC secretome (TGF-β1 Secretome), which have the potential to be therapeutic in terms of regenerative dentistry, in terms of osteogenesis, adipogenesis and gingival wound healing with proteomic analyses.

MATERIALS AND METHODS

pCMV-TGF-β1 plasmid was transfected into hDPSCs by electroporation. hDPSC and TGF-β1 transfected hDPSC secretomes were collected for LC-MS/MS. Protein contents in control secretome and TGF-β1 secretome were analyzed by tandem mass spectrometry-based shotgun proteomic method. Bioinformatic evaluations for canonical pathways, upstream regulators and networks were completed via Ingenuity Pathway Analysis (IPA, QIAGEN) software. Surface marker expressions between groups, treated secretome were measured by flow cytometry. To support the proteomic data morphologically, we performed osteogenic-adipogenic differentiation in hDPSCs treated with control secretome and TGF-β1 secretome, and scratch wound healing assay in gingival fibroblasts. Statistical analyses were performed by GraphPad Prism 8.02.

RESULTS

Venn diagram classification showed us 174 common proteins were identified from each group. In the control secretome 140 unique proteins were identified and 66 entries were exclusive for TGF-β1 secretome. TGF-β1 secretome was found to have therapeutic effect on MSC-specific immunophenotypes. TGF-β1 secretome was determined to up-regulate osteogenesis-related molecules and pathways while down-regulating adipogenesis-related pathways. Analysis of canonical pathways showed that TGF-β1 secretome is associated with the wound healing pathway.

CONCLUSION

Our study provided the first evidence that proteins identified in TGF-β1-transfected hDPSC secretomes are potential regulators of osteogenic/adipogenic differentiation and fibroblast wound healing.

CLINICAL SIGNIFICANCE

Based on these results, TGF-β1 secretome may have a therapeutic effect in repairing osteoporosis-related bone injuries, wound healing of oral mucosa and gingival tissue. TGF-β1 secretome may be a potential cell-free therapeutic in orthopedics and regenerative dentistry.

Injectable platelet-rich fibrin influences the behavior of gingival mesenchymal stem cells

In this study, we examined the effects of injectable platelet-rich fibrin (iPRF) on proliferation and osteodifferentiation in mesenchymal stem cells (MSCs) isolated from human gingiva. Gingival MSCs (gMSCs) were grown in experimental culture media with different concentrations of iPRF [5%, 10%, and replacement of fetal calf serum (FCS) in the standard media with 10% iPRF–10% iPRF-FCS]. Immunophenotyping of gMSCs was performed after seven days by flow cytometry, and their proliferation was examined after three and seven days using the Cell Counting Kit-8 method. After 14 days in culture, spontaneous osteogenic differentiation of gMSCs was evaluated via real-time polymerase chain reaction. All gMSCs were positive for cluster of differentiation (CD) 105, CD73, CD90, and CD44, and negative for CD34/45, CD14, CD79a, and human leukocyte antigen, DR isotype (HLA-DR). Reduced expression of some surface antigens was observed in the gMSCs grown in 10% iPRF-FCS medium compared to the other groups. After three days, gMSCs grown in 10% iPRF had proliferated significantly less than the other groups. After seven days, proliferation was significantly higher in the 5% iPRF cells compared to the control, while proliferation in the 10% iPRF and 10% iPRF-FCS groups was significantly lower. No spontaneous osteogenic differentiation was observed in the presence of iPRF, as observed by low runt-related transcription factor 2 (RUNX2) expression. Some expression of secreted protein acidic and cysteine rich (SPARC) and collagen 1 alpha (COL1A) was observed for all the gMSCs regardless of the culture medium composition. gMSCs grown in 10% iPRF had significantly lower SPARC expression. In conclusion, 5% iPRF stimulated gMSC proliferation, and an excessively high concentration of iPRF can impair osteogenic induction.

Osteogenic differentiation of human mesenchymal stromal cells and fibroblasts differs depending on tissue origin and replicative senescence

The need for an autologous cell source for bone tissue engineering and medical applications has led researchers to explore multipotent mesenchymal stromal cells (MSC), which show stem cell plasticity, in various human tissues. However, MSC with different tissue origins vary in their biological properties and their capability for osteogenic differentiation. Furthermore, MSC-based therapies require large-scale ex vivo expansion, accompanied by cell type-specific replicative senescence, which affects osteogenic differentiation. To elucidate cell type-specific differences in the osteogenic differentiation potential and replicative senescence, we analysed the impact of BMP and TGF-β signaling in adipose-derived stromal cells (ASC), fibroblasts (FB), and dental pulp stromal cells (DSC). We used inhibitors of BMP and TGF-β signaling, such as SB431542, dorsomorphin and/or a supplemental addition of BMP-2. The expression of high-affinity binding receptors for BMP-2 and calcium deposition with alizarin red S were evaluated to assess osteogenic differentiation potential. Our study demonstrated that TGF-β signaling inhibits osteogenic differentiation of ASC, DSC and FB in the early cell culture passages. Moreover, DSC had the best osteogenic differentiation potential and an activation of BMP signaling with BMP-2 could further enhance this capacity. This phenomenon is likely due to an increased expression of activin receptor-like kinase-3 and -6. However, in DSC with replicative senescence (in cell culture passage 10), osteogenic differentiation sharply decreased, and the simultaneous use of BMP-2 and SB431542 did not result in further improvement of this process. In comparison, ASC retain a similar osteogenic differentiation potential regardless of whether they were in the early (cell culture passage 3) or later (cell culture passage 10) stages. Our study elucidated that ASC, DSC, and FB vary functionally in their osteogenic differentiation, depending on their tissue origin and replicative senescence. Therefore, our study provides important insights for cell-based therapies to optimize prospective bone tissue engineering strategies.

Effects of combination TGF-B1 transfection and platelet rich plasma (PRP) on three-dimension chondrogenic differentiation of rabbit dental pulp-derived mesenchymal stem cells

Aim: The aim of this study was to evaluate the effects of standard culture medium and chondrogenic differentiation medium with PRP on chondrogenic differentiation of rabbit dental pulp-derived mesenchymal stem cells (rabbit DPSCs) that are transfected with transforming growth factor-beta 1 (TGF-B1) gene, based on the hypothesis of TGF- B1 and PRP can be effective on the chondrogenesis of stem cells. Materials and Methods: Rabbit DPSCs were characterized by using flow cytometry, immunofluorescent staining, quantitative Real Time Polymerase Chain Reaction (qRT-PCR) and differentiation tests. For the characterization, CD29, CD44 and CD45 mesenchymal cell markers were used. Rabbit DPSCs were transfected with TGF-B1 gene using electroporation technique in group 1; with PRP 10% in group 2; with chondrogenic medium in group 3; with both chondrogenic medium and PRP in group 4. DPSCs were cultured in medium with 10% inactive PRP in group 5, chondrogenic medium in group 6, chondrogenic medium with PRP 10% in group 7. SOX9, MMP13 and Aggrecan gene expression levels were evaluated in 3, 6, 12. and 24. days by qRT-PCR. Results: The expression levels of SOX9, MMP13 and Aggrecan were higher in group 2, 3 and group 7 in 3th day however in 24th day group 7 and group 2 were found higher. The expression levels changed by time-dependent. The extracellular matrix of the cells in experimental groups were positively stained with safranin O and toluidine blue. Conclusion: The combination in culture medium of TGF-B1 gene transfection and 10% PRP accelerates the chondrogenic differentiation of DPSCs.

Does the application of GaAlAs laser and platelet-rich plasma induce cell proliferation and increase alkaline phosphatase activity in human dental pulp stem cells?

Blood extracts containing platelet products are gaining popularity in promoting healing and pulp regeneration. This study was designed to evaluate the effect of platelet-rich plasma (PRP) and gallium-aluminum-arsenide (GaAlAs) laser on proliferation and differentiation of human dental pulp stem cells (hDPSCs). In this ex vivo study, hDPSCs isolated from impacted mandibular third molars were cultured in Dulbecco's Modified Eagle's medium )DMEM(with 10% fetal bovine serum (FBS). After reaching the desired confluence, the cells were distributed into 4 groups, namely, control, PRP, laser, and PRP+laser for MTT assay and alkaline phosphatase (ALP) test. In the PRP and PRP+laser groups, 10% PRP was added to each well on the plate. In the laser and PRP+laser groups, as for the proliferation test, laser irradiation was carried out for 45 s, while 135 s was designated for ALP test. After 1, 3, and 5 days, cell proliferation and ALP activity were assessed using MTT and ALP colorimetric assay, respectively. Two-way ANOVA was utilized to analyze data. In PRP and PRP+laser groups, cell proliferation and viability increased until day 3 but began to decline afterwards until the 5th day. In the laser group, the increase in proliferation and viability was observed till day 5 which was less than the control group. Laser and control groups exhibited significantly higher cell viability and proliferation than both PRP and PRP+laser groups. ALP activity was more pronounced in PRP+laser, PRP, and laser in descending order; however, all were less than that of the control group. Only in the control group did the ALP activity augment during the 5-day period. Laser irradiation could induce pulp cell proliferation and demonstrated a better performance than PRP in this regard.

Allogeneic Fibrin Clot for Odontogenic/Cementogenic Differentiation of Human Dental Mesenchymal Stem Cells

BACKGROUND

Fetal bovine serum is widely used as a growth supplement for cell culture medium; however, animal-borne pathogens increase the risk of transmitting infectious agents. Platelet-rich fibrin is recently considered as a successful alternative but leukocytes present limits to its allogeneic feasibility. The aim of this study was to explore the effects of allogeneic fibrin clot (AFC) without leukocytes on inducing odontogenic/cementogenic differentiation of human dental pulp stem cells (hDPSCs) and human periodontal ligament stem cells (hPDLSCs) in vitro and in vivo.

METHODS

AFC was prepared by high-speed centrifugation and leukocytes were almost removed, and AFC serum was obtained through three freeze-thaw cycles. hDPSCs and hPDLSCs were treated with AFC serum to investigate the odontogenic or cementogenic associated markers by real-time polymerase chain reaction. hDPSCs were treated with AFC serum and placed inside of dentin canal, hPDLSCs were treated with AFC serum to wrap outside of dentin, the mixture was then transplanted into the subcutaneous of nude mice for 12 weeks.

RESULTS

AFC serum exhibited enough growth factors and cytokines to induce odontogenic/cementogenic differentiation of hDPSCs and hPDLSCs in vitro. Furthermore, AFC seurum could induce hDPSCs to differentiate into odontoblasts-like cells and pulp-like tissues, and hPDLSCs to regenerate cementum-like tissues.

CONCLUSION

AFC could be an alternative safe source with growth factors for the expansion of human dental mesenchymal stem cells (hDMSCs).

Effects of Platelet-Rich Plasma on Proliferation, Viability, and Odontogenic Differentiation of Neural Crest Stem-Like Cells Derived from Human Dental Apical Papilla

Objective

This study is aimed at evaluating the effects of platelet-rich plasma (PRP) on proliferation, viability, and odontogenic differentiation of neural crest stem-like cells (NCSCs) derived from human dental apical papilla.

Materials and Methods

Cells from apical papillae were obtained and then induced to form neural spheres. The expression of NCSC markers p75NTR and HNK-1 in neural sphere cells was detected by immunofluorescence staining. Human PRP was prepared by a 2-step centrifugation method and activated by CaCl₂ and thrombin. The concentrations of PDGF-BB and TGF-β1 in whole blood and PRP were measured by an ELISA kit. PRP in five different concentrations (0%, 2.5%, 5%, 10%, and 25%) was applied to culture NCSCs. On the 1^st, 3^rd, 5^th, and 7^th days, cell proliferation was evaluated by CCK8. Cell viability was tested by a live/dead staining kit. mRNA and protein expression of DSPP and BMP4 were analyzed by RT-qPCR and western blot, respectively. Statistical analysis was performed by a one-way analysis of variance (ANOVA) test or t-test.

Results

Dental apical papilla cells formed neural spheres, from which cells displayed positive expression of p75NTR and HNK-1. The concentrations of PDGF-BB and TGF-β1 in PRP were about 3.5-fold higher than those in whole blood. 5% and 10% PRP significantly promoted proliferation of NCSCs, while 25% and 50% PRP inhibited cell proliferation from Day 3 to Day 7. Low-concentration (2.5%, 5%, and 10%) PRP slightly improved viability of NCSCs on Day 7. On the other hand, high-concentration (25% and 50%) PRP significantly inhibited viability of NCSCs from Day 3 to Day 7. RT-qPCR and western blot results indicated that 10% PRP could promote odontogenic differentiation of NCSCs on Day 7. mRNA and protein expression of DSPP and BMP4 were significantly upregulated in the 10% PRP group compared to those in the control group (P < 0.05).

Conclusions

PRP is a simply acquirable blood derivative which contains high concentration of growth factors like PDGF-BB and TGF-β1. PRP in a proper concentration could promote proliferation, viability, and odontogenic differentiation of NCSCs derived from human dental apical papilla.

Comparative evaluation of angiogenesis using a novel platelet-rich product: An in vitro study

Background:

In vivo angiogenesis is normal and vital process in growth and development, wound healing, and formation of granulation tissue wherein new blood vessels form from preexisting vessels as part of revascularization. Platelet-rich products promote wound healing associated with angiogenesis. Biomaterials such as titanium were found to be angiogenic. Unlike in vivo situations, in vitro angiogenesis, study cells, within a controlled environment.

Aims:

The aim of this study is to evaluate the angiogenic potential of a novel platelet-rich product.

Materials and Methods:

Blood was drawn from volunteers with informed consent. Blood samples were centrifuged to obtain platelet-rich products. Platelet concentrates prepared were platelet-rich plasma (PRP), platelet-rich fibrin, and a novel platelet-rich product which is titanium-prepared PRP (TPRP), obtained using titanium. The study which compared platelet concentrate was divided into four groups subjected to tissue culture. Phase-contrast microscope was used to determine the rate of growth by cell counting.

Statistical Analysis:

ANOVA was used for comparison within groups and post hoc for multiple comparisons.

Results:

TPRP group showed granular ground substance. Group with platelet-rich fibrin (PRF) shows a high rate of growth whereas those with TPRP showed better growth rate when compared to its counterpart, PRP.

Conclusions:

This is the first study which introduces TPRP. Previous studies have proved that titanium-prepared PRF has better structural quality than its counterpart platelet-rich fibrin. This study concludes that TPRP has better angiogenic potential than its counterpart PRP. Further in vivo studies are needed to promote TPRP as a new generation of platelet products.

Platelet Rich Plasma Augments Adipose-Derived Stem Cell Growth and Differentiation

BACKGROUND

Adipose-derived stem cells (ASCs) are a powerful tool for cosmetic surgery and regenerative medicine. The use of autologous platelet rich plasma (PRP), particularly in combination with ASC-based therapy, has significantly expanded in recent years. Unfortunately, the mechanisms and optimal dosing responsible for the beneficial effects of PRP remain poorly understood. Here we investigate the effect of PRP on ASC growth and differentiation.

OBJECTIVES

To assess the impact of different PRP feeding and cryopreservation protocols on ASC isolation, expansion, and differentiation.

METHODS

Human PRP was isolated using the Magellan System (Arteriocyte). Fresh PRP (fPRP), flash frozen PRP (ffPRP), and cryopreserved PRP (cPRP) were added to human ASCs isolated from healthy patients. A panel of PRP supplementation protocols was analyzed for ASC adherence, proliferation, and osteogenesis.

RESULTS

The fresh and cryopreserved PRP groups demonstrated reduced cell adherence compared to control (non-PRP) groups (P < 0.001), while the flash frozen PRP groups showed cell adherence equivalent to or better than controls. After 7 days of growth, ASC populations for fPRP and ffPRP Single Administration protocols were significantly higher than other feeding protocols and controls. This benefit was lost in cPRP groups. Optimized ffPRP protocols showed potential for spontaneous osteogenesis.

CONCLUSIONS

Addition of ffPRP improves initial ASC adherence while a single administration of either fresh or flash frozen PRP without additional cell manipulation significantly augments subsequent ASC proliferation. The potential for spontaneous osteogenic differentiation upon PRP exposure invokes the need for additional molecular studies of PRP activity prior to further expansion to clinical applications.

Molecular- and microarray-based analysis of diversity among resting and osteogenically induced porcine mesenchymal stromal cells of several tissue origin

Mesenchymal stromal cells (MSCs) play a pivotal role in modern therapeutic approaches in bone‐healing disorders. Although bone marrow‐derived MSCs are most frequently used, the knowledge that many other adult tissues represent promising sources for potent MSCs has gained acceptance. In the present study, the osteogenic differentiation potential of porcine skin fibroblasts (FBs), as well as bone marrow‐ (BMSCs), adipose tissue‐ (ASCs) and dental pulp‐derived stromal cells (DSCs) were evaluated. However, additional application of BMP‐2 significantly elevated the delayed osteogenic differentiation capacity of ASC and FB cultures, and in DSC cultures the supplementation of platelet‐rich plasma increased osteogenic differentiation potential to a comparable level of the good differentiable BMSCs. Furthermore, microarray gene expression performed in an exemplary manner for ASCs and BMSCs revealed that ASCs and BMSCs use different gene expression patterns for osteogenic differentiation under standard media conditions, as diverse MSCs are imprinted dependent from their tissue niche. However, after increasing the differentiation potential of ASCs to a comparable level as shown in BMSCs, a small subset of identical key molecules was used to differentiate in the osteogenic lineage. Until now, the importance of identified genes seems to be underestimated for osteogenic differentiation. Apparently, the regulation of transmembrane protein 229A, interleukin‐33 and the fibroblast growth factor receptor‐2 in the early phase of osteogenic differentiation is needed for optimum results. Based on these results, bone regeneration strategies of MSCs have to be adjusted, and in vivo studies on the osteogenic capacities of the different types of MCSs are warranted. Copyright © 2016 The Authors Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd.

Use of platelet concentrates in oral and maxillofacial surgery: an overview

OBJECTIVE

To describe and provide a comprehensive overview on the development, use and efficacy of autologous platelet concentrates in different in vitro and in vivo studies focusing on oral and maxillofacial pathologies.

MATERIALS AND METHODS

Present work employs an extensive critical overview of the literature on the development and application of platelet concentrates.

RESULTS

Platelet concentrates are innovative endogenous therapeutic agents which gained a lot of interest in different medical and dental disciplines due to their potential ability to stimulate and increase regeneration of soft and hard tissues. The effect of platelet-derived products is considered to be a result of the high number of platelets which contain a wide range of growth factors. They are not just therapeutic products but autologous blood concentrates containing active molecules. The quality of platelet concentrates may vary according to the individual physical state of donors making it difficult to to compare the outcomes of their application. Although, there are many studies analyzing the properties of these biomaterials both in vivo and in vitro, a consensus regarding their efficacy still has to be reached.

CONCLUSION

Evidences described in the literature on the efficacy of platelet concentrates in procedures in oral and maxillofacial region are controversial and limited. In order to clarify the real advantages and priorities for the patients, when the blood-derived products are applied, further in vitro and in vivo research about the activity of PRP and PRF on the dental cells biology should be conducted.

Application of platelet-rich plasma with stem cells in bone and periodontal tissue engineering

Presently, there is a high paucity of bone grafts in the United States and worldwide. Regenerating bone is of prime concern due to the current demand of bone grafts and the increasing number of diseases causing bone loss. Autogenous bone is the present gold standard of bone regeneration. However, disadvantages like donor site morbidity and its decreased availability limit its use. Even allografts and synthetic grafting materials have their own limitations. As certain specific stem cells can be directed to differentiate into an osteoblastic lineage in the presence of growth factors (GFs), it makes stem cells the ideal agents for bone regeneration. Furthermore, platelet-rich plasma (PRP), which can be easily isolated from whole blood, is often used for bone regeneration, wound healing and bone defect repair. When stem cells are combined with PRP in the presence of GFs, they are able to promote osteogenesis. This review provides in-depth knowledge regarding the use of stem cells and PRP in vitro, in vivo and their application in clinical studies in the future.

A humanized system to expand in vitro amniotic fluid-derived stem cells intended for clinical application

BACKGROUND AIMS

The amniotic fluid is a new source of multipotent stem cells with therapeutic potential for human diseases. In agreement with the regulatory requirement to reduce and possibly to avoid animal-derived reagents in the culture of cells intended for cell therapy, bovine serum, the most common supplement in the culture medium, was replaced by human platelet-derived growth factors.

METHODS

We tested a new culture medium to expand monolayers of human amniotic fluid stem cells (hAFSC) for clinical use. The AFSC were isolated by c-Kit selection and expanded in media supplemented with either bovine serum or a human platelet lysate (Lyset).

RESULTS

We compared proliferation kinetics, colony-forming unit percentage, multilineage differentiation, immunophenotypic characterization and inhibition of peripheral blood mononuclear cell proliferation of the two AFSC cell cultures and we found no significant differences. Moreover, the karyotype analysis of the cells expanded in the presence of the platelet lysate did not present cytogenetic abnormalities and in vitro and in vivo studies revealed no cell tumorigenicity.

CONCLUSIONS

Platelet derivatives represent a rich source of growth factors that can play a safety role in the homeostasis, proliferation and remodeling of tissue healing. We propose human platelet extracts as a preferential alternative to animal serum for the expansion of stem cells for clinical applications.

Highly Efficient In Vitro Reparative Behaviour of Dental Pulp Stem Cells Cultured with Standardised Platelet Lysate Supplementation

Dental pulp is an accessible source of multipotent mesenchymal stromal cells (MSCs). The perspective role of dental pulp stem cells (DPSCs) in regenerative medicine demands an in vitro expansion and in vivo delivery which must deal with the safety issues about animal serum, usually required in cell culture practice. Human platelet lysate (PL) contains autologous growth factors and has been considered as valuable alternative to fetal bovine serum (FBS) in cell cultures. The optimum concentration to be added of such supplement is highly dependent on its preparation whose variability limits comparability of results. By in vitro experiments, we aimed to evaluate a standardised formulation of pooled PL. A low selected concentration of PL (1%) was able to support the growth and maintain the viability of the DPSCs. The use of PL in cell cultures did not impair cell surface signature typically expressed by MSCs and even upregulated the transcription of Sox2. Interestingly, DPSCs cultured in presence of PL exhibited a higher healing rate after injury and are less susceptible to toxicity mediated by exogenous H₂O₂ than those cultured with FBS. Moreover, PL addition was shown as a suitable option for protocols promoting osteogenic and chondrogenic differentiation of DPSCs. Taken together, our results indicated that PL is a valid substitute of FBS to culture and differentiate DPSCs for clinical-grade use.

Biomimetic microenvironments for regenerative endodontics

Regenerative endodontics has been proposed to replace damaged and underdeveloped tooth structures with normal pulp-dentin tissue by providing a natural extracellular matrix (ECM) mimicking environment; stem cells, signaling molecules, and scaffolds. In addition, clinical success of the regenerative endodontic treatments can be evidenced by absence of signs and symptoms; no bony pathology, a disinfected pulp, and the maturation of root dentin in length and thickness. In spite of the various approaches of regenerative endodontics, there are several major challenges that remain to be improved: a) the endodontic root canal is a strong harbor of the endodontic bacterial biofilm and the fundamental etiologic factors of recurrent endodontic diseases, (b) tooth discolorations are caused by antibiotics and filling materials, (c) cervical root fractures are caused by endodontic medicaments, (d) pulp tissue is not vascularized nor innervated, and (e) the dentin matrix is not developed with adequate root thickness and length. Generally, current clinical protocols and recent studies have shown a limited success of the pulp-dentin tissue regeneration. Throughout the various approaches, the construction of biomimetic microenvironments of pulp-dentin tissue is a key concept of the tissue engineering based regenerative endodontics. The biomimetic microenvironments are composed of a synthetic nano-scaled polymeric fiber structure that mimics native pulp ECM and functions as a scaffold of the pulp-dentin tissue complex. They will provide a framework of the pulp ECM, can deliver selective bioactive molecules, and may recruit pluripotent stem cells from the vicinity of the pulp apex. The polymeric nanofibers are produced by methods of self-assembly, electrospinning, and phase separation. In order to be applied to biomedical use, the polymeric nanofibers require biocompatibility, stability, and biodegradability. Therefore, this review focuses on the development and application of the biomimetic microenvironments of pulp-dentin tissue among the current regenerative endodontics.

Human periodontal ligament stem cells suppress T-cell proliferation via down-regulation of non-classical major histocompatibility complex-like glycoprotein CD1b on dendritic cells

BACKGROUND AND OBJECTIVE

Periodontal ligament stem cells (PDLSCs) from the periodontal ligament tissue were recently identified as mesenchymal stem cells (MSCs). The capabilities of PDLSCs in periodontal tissue or bone regeneration have been reported, but their immunomodulatory role in T-cell immune responses via dendritic cells (DCs), known as the most potent antigen-presenting cell, has not been studied. The aim of this study is to understand the immunological function of homogeneous human STRO-1⁺ CD146⁺ PDLSCs in DC-mediated T-cell immune responses to modulate the periodontal disease process.

MATERIAL AND METHODS

We utilized highly purified (> 95%) human STRO-1⁺ CD146⁺ PDLSCs and human bone marrow mesenchymal stem cells (BMSCs). Each stem cell was co-cultured with human monocyte-derived DCs in the presence of lipopolysaccharide isolated from Porphyromonas gingivalis, a major pathogenic bacterium responsible for periodontal disease, in vitro to examine the immunological effect of each stem cell on DCs and DC-mediated T-cell proliferation.

RESULTS

We discovered that STRO-1⁺ CD146⁺ PDLSCs, as well as BMSCs, significantly decreased the level of non-classical major histocompatibility complex glycoprotein CD1b on DCs, resulting in defective T-cell proliferation, whereas most human leukocyte antigens and the co-stimulatory molecules CD80 and CD86 in/on DCs were not significantly affected by the presence of BMSCs or STRO-1⁺ CD146⁺ PDLSCs.

CONCLUSIONS

This study unveiled an immunomodulatory role of STRO-1⁺ CD146⁺ PDLSCs in negatively regulating DC-mediated T-cell immune responses, demonstrating their potential to be utilized in promising new stem cell therapies.

In Vivo Experiments with Dental Pulp Stem Cells for Pulp-Dentin Complex Regeneration

In recent years, many studies have examined the pulp-dentin complex regeneration with DPSCs. While it is important to perform research on cells, scaffolds, and growth factors, it is also critical to develop animal models for preclinical trials. The development of a reproducible animal model of transplantation is essential for obtaining precise and accurate data in vivo. The efficacy of pulp regeneration should be assessed qualitatively and quantitatively using animal models. This review article sought to introduce in vivo experiments that have evaluated the potential of dental pulp stem cells for pulp-dentin complex regeneration. According to a review of various researches about DPSCs, the majority of studies have used subcutaneous mouse and dog teeth for animal models. There is no way to know which animal model will reproduce the clinical environment. If an animal model is developed which is easier to use and is useful in more situations than the currently popular models, it will be a substantial aid to studies examining pulp-dentin complex regeneration.

Human plasma and human platelet-rich plasma as a substitute for fetal calf serum during long-term cultivation of mesenchymal dental pulp stem cells

AIMS

Our aims were to isolate and cultivate mesenchymal dental pulp stem cells (DPSC) in various media enriched with human blood components, and subsequently to investigate their basic biological properties.

METHODS

DPSC were cultivated in five different media based on α MEM containing different concentrations of human plasma (HP), platelet-rich plasma (PRP), or fetal calf serum (FCS). The DPSC biological properties were examined periodically.

RESULTS

We cultivated DPSC in the various cultivation media over 15 population doublings except for the medium supplemented with 10% HP. Our results showed that DPSC cultivated in medium supplemented with 10% PRP showed the shortest average population doubling time (DT) (28.6 ± 4.6 hours), in contrast to DPSC cultivated in 10% HP which indicated the longest DT (156.2 ± 17.8 hours); hence this part of the experiment had been cancelled in the 6th passage. DPSC cultivated in media with 2% FCS+ITS (DT 47.3 ± 10.4 hours), 2% PRP (DT 40.1 ± 5.7 hours) and 2% HP (DT 49.0 ± 15.2 hours) showed almost the same proliferative activity. DPSC's viability in the 9th passage was over 90% except for the DPSC cultivated in the 10% HP media.

CONCLUSIONS

We proved that human blood components are suitable substitution for FCS in cultivation media for long-term DPSC cultivation.

Osteogenic Potential of Dental Mesenchymal Stem Cells in Preclinical Studies: A Systematic Review Using Modified ARRIVE and CONSORT Guidelines

Background and Objective. Dental stem cell-based tissue engineered constructs are emerging as a promising alternative to autologous bone transfer for treating bone defects. The purpose of this review is to systematically assess the preclinical in vivo and in vitro studies which have evaluated the efficacy of dental stem cells on bone regeneration. Methods. A literature search was conducted in Ovid Medline, Embase, PubMed, and Web of Science up to October 2014. Implantation of dental stem cells in animal models for evaluating bone regeneration and/or in vitro studies demonstrating osteogenic potential of dental stem cells were included. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used to ensure the quality of the search. Modified ARRIVE (Animal research: reporting in invivo experiments) and CONSORT (Consolidated reporting of trials) were used to critically analyze the selected studies. Results. From 1914 citations, 207 full-text articles were screened and 137 studies were included in this review. Because of the heterogeneity observed in the studies selected, meta-analysis was not possible. Conclusion. Both in vivo and in vitro studies indicate the potential use of dental stem cells in bone regeneration. However well-designed randomized animal trials are needed before moving into clinical trials.

Platelet preparations in dentistry: How? Why? Where? When?

The aim of this article is to review the outcomes of platelet preparations in dentistry. A structured electronic search discovered 348 articles, which described the use of autologous platelet concentrates with a relevance to clinical dentistry. Among these articles, 220 articles investigated platelet rich plasma, 99 investigated platelet rich fibrin, 22 investigated plasma rich in growth factors and 7 investigated the use of concentrated growth factors. Several studies reported beneficial treament outcomes in terms of enhanced bone and soft tissue regeneration.

Dental Stem Cells in Pulp Regeneration: Near Future or Long Road Ahead?

Although regenerative endodontic procedures have yielded an impressive body of favorable outcomes, the treatment of necrotic immature permanent teeth in particular remains to be a challenge. Recent advances in dental stem cell (DSC) research have gained increasing insight in their regenerative potential and prospective use in the formation of viable dental tissues. Numerous studies have already reported successful dental pulp regeneration following application of dental pulp stem cells, stem cells from the apical papilla, or dental follicle precursor cells in different in vivo models. Next to responsive cells, dental tissue engineering also requires the support of an appropriate scaffold material, ranging from naturally occurring polymers to treated dentin matrix components. However, the routine use and banking of DSCs still holds some major challenges, such as culture-associated differences, patient-related variability, and the effects of culture medium additives. Only in-depth evaluation of these problems and the implementation of standardized models and protocols will effectively lead to better alternatives for patients who no longer benefit from current treatment protocols.

Characteristic expression of MSX1, MSX2, TBX2 and ENTPD1 in dental pulp cells

Dental pulp cells (DPCs) are a promising source of transplantable cells in regenerative medicine. However, DPCs have not been fully characterized at the molecular level. The aim of the present study was to distinguish DPCs from various source-derived mesenchymal stem cells (MSCs), fibroblasts (FBs) and other cells by the expression of several DPC-characteristic genes. DPCs were isolated from human pulp tissues by the explant method or the enzyme digestion method, and maintained with media containing 10% serum or 7.5% platelet-rich plasma. RNA was isolated from the cells and from dental pulp tissue specimens. The mRNA levels were determined by DNA microarray and quantitative polymerase chain reaction analyses. The msh homeobox 1, msh homeobox 2, T-box 2 and ectonucleoside triphosphate diphosphohydrolase 1 mRNA levels in DPCs were higher than that of the levels identified in the following cell types: MSCs derived from bone marrow, synovium and adipose tissue; and in cells such as FBs, osteoblasts, adipocytes and chondrocytes. The enhanced expression in DPCs was consistently observed irrespective of donor age, tooth type and culture medium. In addition, these genes were expressed at high levels in dental pulp tissue in vivo. In conclusion, this gene set may be useful in the identification and characterization of DPCs in basic studies and pulp cell-based regeneration therapy.

Adipose-derived stem cells incorporated into platelet-rich plasma improved bone regeneration and maturation in vivo

BACKGROUND/AIM

Some cases of tooth loss related to dental trauma require bone-grafting procedures to improve the aesthetics before prosthetic rehabilitation or to enable the installation of dental implants. Bone regeneration is often a challenge and could be largely improved by mesenchymal stem cells therapy. However, the appropriate scaffold for these cells still a problem. This study evaluated the in vivo effect of human adipose-derived stem cells incorporated into autogenous platelet-rich plasma in bone regeneration and maturation.

MATERIAL AND METHODS

Adipose-derived stem cells were isolated from lipoaspirate tissues and used at passage 4. Immunophenotyping and multilineage differentiation of cells were performed and mesenchymal stem cells characteristics confirmed. Bicortical bone defects (10 mm diameter) were created in the tibia of six beagle dogs to evaluate the effect of adipose-derived stem cells incorporated into platelet-rich plasma scaffolds, platelet-rich plasma alone, autogenous bone grafts, and clot. Samples were removed 6 weeks postsurgeries and analyzed by quantification of primary and secondary bone formation and granulation tissue.

RESULTS

Adipose-derived stem cells incorporated into platelet-rich plasma scaffolds promoted the highest bone formation (primary + secondary bone) (P < 0.001), the highest bone maturation (secondary bone) (P < 0.001), and the lowest amount of granulation tissue (P < 0.001).

CONCLUSIONS

Adipose-derived stem cells incorporated into platelet-rich plasma scaffolds promote more bone formation and maturation, and less granulation tissue in bone defects created in canine tibia. Therefore, platelet-rich plasma can be considered as a candidate scaffold for adipose-derived stem cells to promote bone regeneration.

Odontogenic differentiation of vascular endothelial growth factor-transfected human dental pulp stem cells in vitro

Dental pulp stem cells (DPSCs) can be induced towards odontogenic differentiation. Previous studies have shown that vascular endothelial growth factor (VEGF) is able to induce the osteogenic differentiation of cells, but the effectiveness of VEGF in the odontogenic differentiation of DPSCs remains unclear. This study aimed to investigate the effects of lentivirus‑mediated human VEGF gene transfection on the proliferation and odontogenic differentiation of human DPSCs in vitro. DPSCs were transfected with either lentiviral pCDH‑CMV‑MCS‑EFI‑copGFP (pCDH) vector or recombinant pCDH‑VEGF vector, and the growth characteristics of the resulting DPSCs/Vector and DPSCs/VEGF were subsequently assessed. The odontogenic differentiation genes of the two groups of cells, including alkaline phosphatase, osteocalcin, dentin sialophosphoprotein and dentin matrix protein 1 (DMP1), were evaluated by quantitative polymerase chain reaction (qPCR). The specific proteins of odontogenic differentiation, including dentin sialoprotein and DMP1, were analyzed by western blotting. DPSCs/VEGF showed similar proliferation characteristics to DPSCs/Vector during the observation period. qPCR results showed that the relative VEGF gene expression was significantly higher in DPSCs/VEGF than that in DPSCs/Vector two days after transfection (P<0.01). Similarly, western blot analysis showed that the protein expression levels of VEGF were higher in DPSCs/VEGF than those in DPSCs/Vector. On the first, fourth, eighth and 16th days after lentivirus-mediated transfection, the expression of odontogenic differentiation-specific genes and proteins was higher in DPSCs/VEGF than that in DPSCs/Vector. These results indicated that lentivirus-mediated VEGF gene transfection promoted the odontogenic differentiation of human DPSCs in vitro.

Comparison of tissue-engineered bone from different stem cell sources for maxillary sinus floor augmentation: a study in a canine model

PURPOSE

To compare the potential of tissue-engineered bone derived from different stem cell sources for canine maxillary sinus augmentation.

MATERIALS AND METHODS

Bilateral maxillary sinus floor augmentations were performed in 6 beagles and were randomly repaired with 3 graft types: Bio-Oss granules alone (n = 4; group A), a complex of osteoblasts derived from bone marrow mesenchymal stem cells (BMMSCs) and Bio-Oss (n = 4; group B), and a complex of osteoblasts derived from periodontal ligament stem cells (PDLSCs) and Bio-Oss (n = 4; group C). After 12 weeks, fluorescent labeling, maxillofacial computed tomography, scanning electron microscopy, and histologic and histomorphometric analyses were used to evaluate new bone deposition, mineralization, and remodeling in the augmented area.

RESULTS

The osteogenic capacity was greater in groups B and C than in group A. The level tended to be higher in group C than in group B; however, the difference was not statistically significant.

CONCLUSIONS

Seeding of PDLSCs or BMMSCs onto Bio-Oss can promote bone formation and mineralization and maintain the maximum volume of the augmented maxillary sinus. These tissue-engineered bone complexes might be a good option for augmentation of the maxillary sinus in edentulous patients.

Effect of concentrated growth factors on beagle periodontal ligament stem cells in vitro

Identifying a reliable and effective cytokine or growth factor group has been the focus of stem cell osteogenic induction studies. Concentrated growth factors (CGFs) as the novel generation of platelet concentrate products, appear to exhibit a superior clinical and biotechnological application potential, however, there are few studies that have demonstrated this effect. This study investigated the proliferation and differentiation of periodontal ligament stem cells (PDLSCs) co‑cultured with CGFs. The rate of proliferation was analyzed by cell counting and an MTT assay. Mineralization nodule counts, alkaline phosphatase activity detection, qPCR, western blot analysis and immunohistochemistry were used to analyze mineralization effects. The results showed that CGF significantly promoted the proliferation of PDLSCs, and exhibited a dose‑dependent effect on the activation and differentiation of the stem cells. The application of CGF on PDLSC proliferation and osteoinduction may offer numerous clinical and biotechnological application strategies.

Dental pulp stem cells from traumatically exposed pulps exhibited an enhanced osteogenic potential and weakened odontogenic capacity

OBJECTIVES

Traumatic pulp exposure can bring about some permanent damages to tooth tissues including dental pulps. This study was designed to evaluate the effects of traumatic pulp exposure on the osteo/odontogenic capacity of dental pulp stem cells (DPSCs).

METHODS

Rat incisors were artificially fractured and dental pulps were exposed to the oral environment for 48 h. Then, multi-colony-derived DPSCs from the injured pulps (iDPSCs) were isolated. Their osteo/odontogenic differentiation and the involvement of NF-κB pathway were subsequently investigated.

RESULTS

iDPSCs presented a lower proliferative capacity than normal DPSCs (nDPSCs), as indicated by MTT and FCM assay. ALP levels in iDPSCs were significantly higher (P<0.01) than those in nDPSCs. Alizarin red staining revealed that iDPSCs exhibited an increased capacity of calcium deposition. Moreover, iDPSCs expressed stronger osteogenic markers (Runx2/RUNX2 and Ocn/OCN) and less odontogenic gene/protein (Dspp/DSP) than nDPSCs in vitro. In vivo transplantation showed that nDPSCs implants generated the typical dentine-pulp complex while all iDPSCs pellets formed the osteodentin-like tissues which were immunopositive for OCN. Mechanistically, iDPSCs expressed the higher levels of cytoplasmic phosphorylated IκBα/P65 and nuclear P65 than nDPSCs, indicating an active cellular NF-κB pathway in iDPSCs. After the inhibition of NF-κB pathway, the osteogenic potential in iDPSCs was significantly down-regulated while odontogenic differentiation was up-regulated, as indicated by the decreased Alp/Runx2/Ocn and uprised Dspp expression.

CONCLUSIONS

Pulp exposure for 48 h decreased the odontogenic capacity and enhanced the osteogenic potential of DPSCs via the NF-κB signalling pathway.

Biological activity of a standardized freeze-dried platelet derivative to be used as cell culture medium supplement

Serum of animal origin and in particular fetal bovine serum is the most commonly utilized cell culture medium additive for in vitro cell growth and differentiation. However, several major concerns have been raised by the scientific community regarding the use of animal sera for human cell-based culture applications. Among the possible alternatives to the animal serum, platelet-derived compounds have been proposed since more than 10 years. Nevertheless, the high degree of variability between the different platelet preparations, and the lack of standardized manufacturing and quality control procedures, made difficult to reach a consensus on the applicability of this novel cell culture medium supplement. In this study, we describe the preparation of a standardized platelet-rich plasma (PRP) derivative obtained starting from human-certified buffy coat samples with a defined platelet concentration and following protocols including also freeze-drying, gamma irradiation and biological activity testing prior the product release as cell culture medium additive. Biological activity testing of the different preparations was done by determining the capability of the different PRP preparations to sustain human bone marrow mesenchymal stem cell (MSC) clone formation and proliferation. Taking advantage of a developed MSC in vitro clonogenicity test, we also determined biological activity and stability of the freeze-dried gamma-sterilized PRP preparations after their storage for different times and at different temperatures. The PRP effects on cell proliferation were determined both on primary cell cultures established from different tissues and on a cell line. Results were compared with those obtained in "traditional" parallel control cultures performed in the presence of bovine serum [10% fetal calf serum (FCS)]. Compared to FCS, the PRP addition to the culture medium increased the MSC colony number and average size. In primary cell cultures and in cell line cultures, the PRP promoted cell proliferation also in conditions where the FCS had not a proliferation stimulating effect due to either the nature of the cells and the tissue of origin (such as human articular chondrocytes from elderly patients) or to the critical low density cell seeding (such as for HeLa cells). In summary, the standardized PRP formulation would provide an "off-the-shelf" product to be used for the selection and expansion of several cell types also in critical cell culture conditions.

Effect of autologous platelet-rich plasma on distraction osteogenesis in the mandible of rabbits: a morphologic and morphometric approach

Distraction osteogenesis of the jaw is a common surgical practice in the treatment of pediatric craniofacial deformities. Autologous platelet rich plasma (PRP) has been used to increase the healing potential of bones in humans during distraction osteogenesis. This article aims to study the morphometric and morphologic parameters resulting from the effect of PRP on bone healing after mandibular distraction in rabbits. Right mandibular distraction was performed in 12 rabbits divided equally into 2 groups. PRP and physiological saline were injected, according to a defined protocol, in the callus following distraction of the experimental and control groups respectively. The rabbits were sacrificed after a consolidation period of 45 days and the mandibles were surgically removed. Bone mineral density, radiographic analysis, mechanical properties and histological features of the lengthened bones were assessed using radiographic examination, dual X-ray absorptiometry, biomechanical testing and histology. Results showed that the regenerate bone density, the amount of trabeculation in addition to the bone mineral density and mineral content, as measured by absorptiometry, were better with PRP but not significantly different between groups. Two radiographs revealed a more consistent healing in the experimental mandibles compared with erratic outcomes in corresponding controls. Two of the latter could not be subjected to any mechanical testing because the mandibular parts, connected with fibrous tissue, were separated. Consequently, the biomechanical test depicted greater maximal loads in the experimental group. The histological studies exhibited more ossification and less connective tissue fibers in the experimental group. PRP accelerated healing of mandibles in rabbits following distraction and improved their biomechanical properties. These findings have significant clinical implications on reducing the period of consolidation of the mandibles which may not be immobilized like other bones for long periods of time.

Human serum promotes osteogenic differentiation of human dental pulp stem cells in vitro and in vivo

Human dental pulp is a promising alternative source of stem cells for cell-based tissue engineering in regenerative medicine, for the easily recruitment with low invasivity for the patient and for the self-renewal and differentiation potential of cells. So far, in vitro culture of mesenchymal stem cells is usually based on supplementing culture and differentiation media with foetal calf serum (FCS). FCS is known to contain a great quantity of growth factors, and thus to promote cell attachment on plastic surface as well as expansion and differentiation. Nevertheless, FCS as an animal origin supplement may represent a potential means for disease transmission besides leading to a xenogenic immune response. Therefore, a significant interest is focused on investigating alternative supplements, in order to obtain a sufficient cell number for clinical application, avoiding the inconvenients of FCS use. In our study we have demonstrated that human serum (HS) is a suitable alternative to FCS, indeed its addition to culture medium induces a high hDPSCs proliferation rate and improves the in vitro osteogenic differentiation. Furthermore, hDPSCs-collagen constructs, pre-differentiated with HS-medium in vitro for 10 days, when implanted in immunocompromised rats, are able to restore critical size parietal bone defects. Therefore these data indicate that HS is a valid substitute for FCS to culture and differentiate in vitro hDPSCs in order to obtain a successful bone regeneration in vivo.

Transplantation of dental pulp stem cells and platelet-rich plasma for pulp regeneration

INTRODUCTION

The loss of dental pulp may weaken teeth, rendering them susceptible to reinfection, fracture, and subsequent tooth loss. Therefore, regeneration of pulp is considered an ideal treatment to preserve teeth. The aim of this study was to explore the capacity of dental pulp stem cells (DPSCs) and platelet-rich plasma (PRP) to regenerate dental pulp in canine mature permanent teeth.

METHODS

Pulpectomy with apical foramen enlarged to a #80 file was performed in 16 upper premolars of 4 beagle dogs. Four experimental groups were randomly established: (1) the blood clot group, (2) the autologous DPSCs group, (3) the PRP group, and (4) the DP + PRP group (a mixture of DPSCs and PRP). Four lower premolars without any further treatment after pulpectomy were used as the control group. All teeth were sealed with mineral trioxide aggregate and composite. Twelve weeks after transplantation, the teeth were subjected to radiographic and histologic examination.

RESULTS

Twenty-four of 32 experimental root canals gained newly formed tissues. All canals with an introduction of a blood clot showed histologic evidence of vital tissue formation. Cementum-like and periodontal ligament-like tissues along the internal root canal walls were typical structures in most cases. There is no significant difference between groups with or without autologous DPSC transplantation (exact chi-square test, P < .05).

CONCLUSIONS

New vital tissues can be regenerated in permanent canine teeth after pulpectomy and enlargement of the apical foramen. Histologically, transplantation of DPSCs and/or PRP into root canals showed no enhancement in new tissue formation compared with inducement of a blood clot into the root canals alone.

A novel method for banking dental pulp stem cells

Dental pulp stem cells (DPSC), a cell type of mesenchymal origin showing high proliferation and plasticity, are an emerging source of adult stem cells offering interesting features in view of potential applications in regenerative medicine. These features prompted us to develop a new method to cryopreserve DPSC inside a whole tooth, thus avoiding the need to purify the cells before cryopreservation and reducing the initial costs and workload of tooth banking. In this study we cryopreserved 4 human deciduous whole teeth after digging micro-channels into the tooth with an Nd:YAG laser beam (laser piercing) to allow the cryopreservative to reach the dental pulp and preserve the cells at -80°C. Then, we isolated, expanded and characterized in vitro the stem cells after tooth thawing and mechanical fracture. In parallel, we characterized cells extracted from 2 teeth cryopreserved without laser piercing and from 4 non cryopreserved, non laser pierced, freshly fractured teeth. Our data demonstrate that DPSC isolated from laser pierced cryopreserved teeth show mesenchymal stem cells morphology, immunophenotype, viability and proliferation rate similar to those of cells isolated from fresh, non cryopreserved teeth, whereas significant loss of cell viability and proliferation rate was shown by cells isolated from teeth cryopreserved without laser piercing. These data support the use of this method for prospective whole tooth banking.

The effects of human platelet lysate on dental pulp stem cells derived from impacted human third molars

Human platelet lysate (PL) has been suggested as a substitute for fetal bovine serum (FBS) in the large-scale expansion of dental pulp stem cells (DPSCs). However, the biological effects and the optimal concentrations of PL for the proliferation and differentiation of human DPSCs remain unexplored. We isolated and expanded stem cells from the dental pulp of extracted third molars and evaluated the effects of PL on the cells' proliferative capacity and differentiation potential in vitro and in vivo. Before testing, immunocytochemical staining and flow cytometry-based cell sorting showed that the cells derived from human dental pulp contained mesenchymal stem cell populations. Cells were grown on tissue culture plastic or on hydroxyapatite-tricalcium phosphate (HA/TCP) biomaterials and were incubated with either normal or odontogenic/osteogenic media in the presence or absence of various concentrations of human PL for further investigation. The proliferation of DPSCs was significantly increased when the cells were cultured in 5% PL under all testing conditions (P < 0.05). However, this enhancement was inconsistent when the cells were cultured in 1% PL or in 10% PL; 10% PL significantly inhibited cell proliferation and was therefore excluded from further differentiation testing. Culture medium containing 5% PL also significantly promoted the mineralized differentiation of DPSCs, as indicated by the measurement of alkaline phosphatase activity and calcium deposition under mineral-conditioned media (P < 0.05). Scanning electron microscopy and modified Ponceau trichrome staining showed that the cells treated with 5% PL and mineralizing media were highly capable of integrating with the HA/TCP biomaterials and had fully covered the surface of the scaffold with an extensive sheet-like structure 14 d after seeding. In addition, 5% PL showed significantly positive effects on tissue regeneration in two in vivo transplantation models. We conclude that the appropriate concentration of PL enhances the proliferation and mineralized differentiation of human DPSCs both in vitro and in vivo, which supports the use of PL as an alternative to FBS or a nonzoonotic adjuvant for cell culture in future clinical trials. However, the elucidation of the molecular complexity of PL products and the identification of both the essential growth factors that determine the fate of a specific stem cell and the criteria to establish dosing require further investigation.

Plasma rich in growth factors promote gingival tissue regeneration by stimulating fibroblast proliferation and migration and by blocking transforming growth factor-β1-induced myodifferentiation

BACKGROUND

Periodontitis involves inflammation and infection of the ligaments and bones that support the teeth. Gingival fibroblasts are the most abundant cells in periodontal tissue, and they play a role in maintaining the structural integrity of the tissue. Plasma rich in growth factors contain a pool of proteins and growth factors that promote wound healing and tissue regeneration. In the present study, we evaluate the potential of different formulations obtained with this approach to stimulate several biologic processes involved in wound healing, including fibroblast proliferation, migration, adhesion, and the autocrine release of some angiogenic factors and extracellular matrix components. Furthermore, the ability of this technology to prevent and inhibit transforming growth factor β1-induced myodifferentiation was also determined.

METHODS

Cell proliferation was evaluated through a colorimetric assay, cell migration was performed on culture inserts, and cell adhesion was studied through a fluorescence-based method. Enzyme-linked immunosorbent assay was used to determine some of the biomolecules released by gingival fibroblasts. Smooth muscle actin expression was assessed through immunofluorescence microscopy.

RESULTS

Results showed that plasma rich in growth factors significantly increased gingival fibroblast proliferation, migration, and cell adhesion on type I collagen matrix. In addition, it stimulated the autocrine expression of vascular endothelial growth factor, hepatocyte growth factor, and hyaluronic acid. The myofibroblast phenotype, which is characterized by expressing α-smooth muscle actin, was inhibited and reverted by treating with this technology.

CONCLUSION

These findings suggest that plasma rich in growth factors is capable of promoting regeneration of gingival connective tissue by stimulating some of the main processes involved in wound regeneration.