Adipogenic Mesenchymal Stem Cells and Hyaluronic Acid as a Cellular Compound for Bone Tissue Engineering:

Effects of Puerarin Combined with PLGA/TCP/Puerarin on Osteocalcin and Sialoprotein of Mandibular Defects

In order to evaluate the effects of puerarin combined with poly lactic-co-glycolic acid (PLGA)/tricalcium phosphate (TCP)/puerarin on osteocalcin and sialoprotein of mandibular defects, the obtained rat jaw cells are analyzed. The surface morphology of osteoblast complex in the scaffold material group and puerarin combined scaffold material group is observed by a scanning electron microscope, and the growth and proliferation of osteoblasts are detected by the Cell Counting Kit-8 (CCK-8) method. Besides, the expression of type-I collagen (COL-I), osteocalcin (OC), and osteopontin (OPN) mRNA and related proteins in osteoblasts are detected by immunocytochemical staining. The results of immunocytochemical staining show that puerarin and PLGA/TCP/puerarin scaffold had significant effects on the expression of COL-I and OC mRNA and related proteins in osteoblasts. The experimental results indicate that puerarin and PLGA/TCP/puerarin can synergistically affect the mRNA and protein expressions of COL-I, OC, and OPN in osteoblasts and have a positive effect on promoting the proliferation activity of osteoblasts.

Sources, Characteristics, and Therapeutic Applications of Mesenchymal Cells in Tissue Engineering

Tissue engineering (TE) is a therapeutic option within regenerative medicine that allows to mimic the original cell environment and functional organization of the cell types necessary for the recovery or regeneration of damaged tissue using cell sources, scaffolds, and bioreactors. Among the cell sources, the utilization of mesenchymal cells (MSCs) has gained great interest because these multipotent cells are capable of differentiating into diverse tissues, in addition to their self-renewal capacity to maintain their cell population, thus representing a therapeutic alternative for those diseases that can only be controlled with palliative treatments. This review aimed to summarize the state of the art of the main sources of MSCs as well as particular characteristics of each subtype and applications of MSCs in TE in seven different areas (neural, osseous, epithelial, cartilage, osteochondral, muscle, and cardiac) with a systemic revision of advances made in the last 10 years. It was observed that bone marrow-derived MSCs are the principal type of MSCs used in TE, and the most commonly employed techniques for MSCs characterization are immunodetection techniques. Moreover, the utilization of natural biomaterials is higher (41.96%) than that of synthetic biomaterials (18.75%) for the construction of the scaffolds in which cells are seeded. Further, this review shows alternatives of MSCs derived from other tissues and diverse strategies that can improve this area of regenerative medicine.

The Therapeutic Potential of Mesenchymal Stromal Cells for Regenerative Medicine: Current Knowledge and Future Understandings

In recent decades, research on the therapeutic potential of progenitor cells has advanced considerably. Among progenitor cells, mesenchymal stromal cells (MSCs) have attracted significant interest and have proven to be a promising tool for regenerative medicine. MSCs are isolated from various anatomical sites, including bone marrow, adipose tissue, and umbilical cord. Advances in separation, culture, and expansion techniques for MSCs have enabled their large-scale therapeutic application. This progress accompanied by the rapid improvement of transplantation practices has enhanced the utilization of MSCs in regenerative medicine. During tissue healing, MSCs may exhibit several therapeutic functions to support the repair and regeneration of injured tissue. The process underlying these effects likely involves the migration and homing of MSCs, as well as their immunotropic functions. The direct differentiation of MSCs as a cell replacement therapeutic mechanism is discussed. The fate and behavior of MSCs are further regulated by their microenvironment, which may consequently influence their repair potential. A paracrine pathway based on the release of different messengers, including regulatory factors, chemokines, cytokines, growth factors, and nucleic acids that can be secreted or packaged into extracellular vesicles, is also implicated in the therapeutic properties of MSCs. In this review, we will discuss relevant outcomes regarding the properties and roles of MSCs during tissue repair and regeneration. We will critically examine the influence of the local microenvironment, especially immunological and inflammatory signals, as well as the mechanisms underlying these therapeutic effects. Importantly, we will describe the interactions of local progenitor and immune cells with MSCs and their modulation during tissue injury. We will also highlight the crucial role of paracrine pathways, including the role of extracellular vesicles, in this healing process. Moreover, we will discuss the therapeutic potential of MSCs and MSC-derived extracellular vesicles in the treatment of COVID-19 (coronavirus disease 2019) patients. Overall, this review will provide a better understanding of MSC-based therapies as a novel immunoregenerative strategy.

Effect of hyaluronic acid on paracrine signaling of osteoblasts from mesenchymal stromal cells: potential impact on bone regeneration

OBJECTIVES

This study evaluated hyaluronic acids (HA) with different molecular weights as potential matrices for tissue-engineered bone grafting and their possible influence on the paracrine mechanisms of adipose-derived mesenchymal stromal cells.

MATERIAL AND METHODS

Murine adipose mesenchymal stromal cells (mASCs) on the fourth passage were seeded in 96-well plates, osteoinduced for 27 days and exposed for 3 days to low (HA-LW) and high/low molecular weight (HA-HLW) at previously defined concentrations. Cytokines IGF-1, VEGF, FGF-2, and BMP-2 were evaluated by quantification in the supernatant.

RESULTS

Greater expression of growth factors was observed in groups with HA-HLW compared to HA-LW. Results indicated that differentiated cells secreted fewer cytokines, namely VEGF, FGF, and BMP-2 than undifferentiated mASCs (p < 0.05). IGF-1 showed its greatest expression in the mASC HA-LW group (p < 0.05).

CONCLUSIONS

The application of HA-HLW as cell matrix in tissue engineering did not compromise mASC paracrine effect. Also, the association of HA-HLW matrix and mASCs resulted in greater expression of osteogenic growth factors. Longer periods of cell differentiation seemed to negatively affect their capacity for local paracrine stimulation.

CLINICAL RELEVANCE

The use of HA-HLW as matrix for undifferentiated ASCs can be positive for bone regeneration, favoring its application as cell matrix in bone grafting procedures.

Hyaluronic acid containing scaffolds ameliorate stem cell function for tissue repair and regeneration

Recent evidence based studies have proposed hyaluronic acid (HA) as an emerging biopolymer for various tissue engineering application. Meanwhile, stem cells (SCs) have also gained immense popularity for their tissue regenerative capacity. Thus, combining HA and stem cells for tissue engineering application have shown to foster tissue repair and regeneration process. HA possesses the ability to interact with SCs via cellular surface receptors along with the capacity to elicit the process of differentiation. The influence of HA on stem cells has been widely investigated in cartilage and bone repair but their properties of reducing inflammation has also been explored in various other tissue repair processes. In this review, we have provided an insight to the effect of crosslinked and non-crosslinked HA on various stem cells. Further, HA based scaffolds combined with stem cells have shown to have a synergistic effect in the regeneration capacity. Also, various chemically modified HA and biomolecules conjugated HA as a suitable carrier or matrix for stem cells delivery and the effect of HA in fine tuning the stem cells function is discussed.

Extraction Socket Preservation Using Growth Factors and Stem Cells: a Systematic Review

Objectives

To evaluate the reported literature on the use of stem cells or growth factors for post extraction treatment of the alveolar bone.

Material and Methods

A NCBI PubMed and PubMed Central databases search was conducted between September 2010 and August 2018, to identify animal or clinical studies reporting the clinical, radiographical and/or histological outcomes of socket preservation techniques after applying mesenchymal stem cells or growth factors. Only studies published in English language in the last 10 years were included in the study.

Results

Eleven studies were identified fulfilling the inclusion criteria. They evaluate a total of 386 post extraction sockets. The main tested materials identified in the current review were bone morphogenetic protein-2 - 3 studies and mesenchymal stem cells - 3 studies. Other comparators were bone morphogenetic protein-9, platelet-derived growth factor-BB homodimers and bone marrow. Overall evaluation indicate positive results for all test groups showing differences in final socket width between 0.64 and 1.28 mm favouring the test groups. Histologically, no particular differences are detected between test and control groups. Most of the studies present low risk of bias.

Conclusions

In general, the use of mesenchymal stem cells or bioactive osteogenic molecules favours bone regeneration after tooth extraction, as evaluated clinically, radiographically and histologically. However, specific differences that support particular recommendations are still unclear in light of the current published evidence. Future studies should include the standardization of the mesenchymal stem cells selection and purification as well as dosage and delivery methods of bioactive molecules.