TGF-β3: A promising growth factor in engineered organogenesis

TGF-β3 Restrains Osteoclastic Resorption Through Autophagy

While TGF-β3 promoted defect healing in a primate baboon skull defect model and patients, it remains unclear whether TGF-β3 affects the formation of osteoclasts and bone resorption between osteogenesis and osteolysis. Analysis of the full transcriptome of hPDLSCs (human periodontal ligament stem cells) revealed that the expression of RANKL was significantly up-regulated after TGF-β3 treatment during osteogenesis, which suggests its involvement in clock-controlled autophagy in bone metabolism. TRAP staining and bone resorption lacunae were used to assess the osteoclasts formed from RANKL-induced differentiated BMMs. During osteoclast differentiation, the characteristics of autophagy regulated by TGF-β3 were observed in BMMs through MDC staining, transmission electron microscopy, and LC3 immunofluorescence. The expression of related genes and proteins were detected on the sixth day in mCherry-EGFP-LC3B lentivirus-transfected BMMs using RT-qPCR and WB. Finally, a trans-well co-culture system was used to evaluate the effects of osteogenic differentiated hPDLSCs treated with TGF-β3 on the osteoclastic differentiation of BMMs. The results showed 10 ng/mL of TGF-β3 significantly suppressed osteoclastic differentiation and bone resorption in BMMs (p < 0.05 vs. RANKL). In particular, TGF-β3 augments the expression of LC3-II to stimulate autophagy, consequently restraining osteoclastic resorption. These findings provide a molecular basis and are beneficial to illustrate the potential druggability of TGF-β3 in osteoporotic diseases.

Adipose-derived stem cells enriched with therapeutic mRNA TGF-β3 and IL-10 synergistically promote scar-less wound healing in preclinical models

Skin wound healing often leads to scar formation, presenting physical and psychological challenges for patients. Advancements in messenger RNA (mRNA) modifications offer a potential solution for pulsatile cytokine delivery to create a favorable wound-healing microenvironment, thereby preventing cutaneous fibrosis. This study aimed to investigate the effectiveness of human adipose-derived stem cells (hADSCs) enriched with N 1-methylpseudouridine (m1ψ) modified transforming growth factor-β3 (TGF-β3) and interleukin-10 (IL-10) mRNA in promoting scar-free healing in preclinical models. The results demonstrated that the modified mRNA (modRNA)-loaded hADSCs efficiently and temporarily secreted TGF-β3 and IL-10 proteins. In a dorsal injury model, hADSCs loaded with modRNA TGF-β3 and IL-10 exhibited multidimensional therapeutic effects, including improved collagen deposition, extracellular matrix organization, and neovascularization. In vitro experiments confirmed the ability of these cells to markedly inhibit the proliferation and migration of keloid fibroblasts, and reverse the myofibroblast phenotype. Finally, collagen degradation mediated by matrix metalloproteinase upregulation was observed in an ex vivo keloid explant culture model. In conclusion, the synergistic effects of the modRNA TGF-β3, IL-10, and hADSCs hold promise for establishing a scar-free wound-healing microenvironment, representing a robust foundation for the management of wounds in populations susceptible to scar formation.

HC-HA/PTX3 Purified From Human Amniotic Membrane Reverts Human Corneal Fibroblasts and Myofibroblasts to Keratocytes by Activating BMP Signaling

Purpose

Fibrosis or scarring is a pathological outcome of wound healing and is characterized by terminally differentiated myofibroblasts. Heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) is a unique matrix component purified from amniotic membrane that exerts an anti-inflammatory effect. Herein, we investigate whether HC-HA/PTX3 can also exert an antiscarring effect.

Methods

Human corneal fibroblasts and myofibroblasts were seeded on plastic, immobilized HA or HC-HA/PTX3 or on plastic with or without soluble HA and HC-HA/PTX3 in DMEM+10% FBS, with or without AMD3100 or SB431542 in DMEM+ITS with or without transforming growth factor–β1 (TGF-β1). Transcript expression of keratocyte and signaling markers was determined by RT-qPCR. Immunostaining was performed to monitor cytolocalization of signaling markers and α-SMA. Western blotting was used to measure relative protein level.

Results

Human corneal fibroblasts and myofibroblasts cultured in or on HC-HA/PTX3, but not HA, were refrained from cytoplasmic expression of αSMA and nuclear translocation of pSMAD2/3 when challenged with exogenous TGF-β1. Such an antiscarring action by suppressing canonical TGF-β1 signaling was surprisingly accompanied by phenotypic reversal to keratocan-expressing keratocytes through activation of BMP signaling. Further investigation disclosed that such phenotypic reversal was initiated by cell aggregation mediated by SDF1-CXCR4 signaling highlighted by nuclear translocation of CXCR4 and upregulation of CXCR4 transcript and protein followed by activation of canonical BMP signaling.

Conclusions

These findings collectively provide mechanistic understanding explaining how amniotic membrane transplantation exerts an antiscarring action. In addition, HC-HA/PTX3 and derivatives may be developed into a new biologic to treat corneal blindness caused by stromal scar or opacity in the future.

Evaluation of tenogenic differentiation potential of selected subpopulations of human adipose-derived stem cells

Identification of a suitable cell source and bioactive agents guiding cell differentiation towards tenogenic phenotype represents a prerequisite for advancement of cell-based therapies for tendon repair. Human adipose-derived stem cells (hASCs) are a promising, yet intrinsically heterogenous population with diversified differentiation capacities. In this work, we investigated antigenically-defined subsets of hASCs expressing markers related to tendon phenotype or associated with pluripotency that might be more prone to tenogenic differentiation, when compared to unsorted hASCs. Subpopulations positive for tenomodulin (TNMD+ hASCs) and stage specific early antigen 4 (SSEA-4+ hASCs), as well as unsorted ASCs were cultured up to 21 days in basic medium or media supplemented with TGF-β3 (10 ng/ml), or GDF-5 (50 ng/ml). Cell response was evaluated by analysis of expression of tendon-related markers at gene level and protein level by real time RT-PCR, western blot, and immunocytochemistry. A significant upregulation of scleraxis was observed for both subpopulations and unsorted hASCs in the presence of TGF-β3. More prominent alterations in gene expression profile in response to TGF-β3 were observed for TNMD+ hASCs. Subpopulations evidenced an increased collagen III and TNC deposition in basal medium conditions in comparison with unsorted hASCs. In the particular case of TNMD+ hASCs, GDF-5 seems to influence more the deposition of TNC. Within hASCs populations, discrete subsets could be distinguished offering varied sensitivity to specific biochemical stimulation leading to differential expression of tenogenic components suggesting that cell subsets may have distinctive roles in the complex biological responses leading to tenogenic commitment to be further explored in cell based strategies for tendon tissues.

Cartilage tissue engineering: recent advances and perspectives from gene regulation/therapy

Diseases in articular cartilages affect millions of people. Despite the relatively simple biochemical and cellular composition of articular cartilages, the self-repair ability of cartilage is limited. Successful cartilage tissue engineering requires intricately coordinated interactions between matrerials, cells, biological factors, and phycial/mechanical factors, and still faces a multitude of challenges. This article presents an overview of the cartilage biology, current treatments, recent advances in the materials, biological factors, and cells used in cartilage tissue engineering/regeneration, with strong emphasis on the perspectives of gene regulation (e.g., microRNA) and gene therapy.

TGFβ3 secretion by three-dimensional cultures of human dental apical papilla mesenchymal stem cells

Mesenchymal stem cells (MSCs) can be isolated from dental tissues, such as pulp and periodontal ligament; the dental apical papilla (DAP) is a less-studied MSC source. These dental-derived MSCs are of great interest because of their potential as an accessible source for cell-based therapies and tissue-engineering (TE) approaches. Much of the interest regarding MSCs relies on the trophic-mediated repair and regenerative effects observed when they are implanted. TGFβ3 is a key growth factor involved in tissue regeneration and scarless tissue repair. We hypothesized that human DAP-derived MSCs (hSCAPs) can produce and secrete TGFβ3 in response to micro-environmental cues. For this, we encapsulated hSCAPs in different types of matrix and evaluated TGFβ3 secretion. We found that dynamic changes of cell-matrix interactions and mechanical stress that cells sense during the transition from a monolayer culture (two-dimensional, 2D) towards a three-dimensional (3D) culture condition, rather than the different chemical composition of the scaffolds, may trigger the TGFβ3 secretion, while monolayer cultures showed almost 10-fold less secretion of TGFβ3. The study of these interactions is provided as a cornerstone in designing future strategies in TE and cell therapy that are more efficient and effective for repair/regeneration of damaged tissues. Copyright © 2015 John Wiley & Sons, Ltd.

Transforming growth factor-β3 (TGF-β3) knock-in ameliorates inflammation due to TGF-β1 deficiency while promoting glucose tolerance

Three homologues of TGF-β exist in mammals as follows: TGF-β1, TGF-β2, and TGF-β3. All three proteins share high homology in their amino acid sequence, yet each TGF-β isoform has unique heterologous motifs that are highly conserved during evolution. Although these TGF-β proteins share similar properties in vitro, isoform-specific properties have been suggested through in vivo studies and by the unique phenotypes for each TGF-β knock-out mouse. To test our hypothesis that each of these homologues has nonredundant functions, and to identify such isoform-specific roles, we genetically exchanged the coding sequence of the mature TGF-β1 ligand with a sequence from TGF-β3 using targeted recombination to create chimeric TGF-β1/3 knock-in mice (TGF-β1(Lβ3/Lβ3)). In the TGF-β1(Lβ3/Lβ3) mouse, localization and activation still occur through the TGF-β1 latent associated peptide, but cell signaling is triggered through the TGF-β3 ligand that binds to TGF-β receptors. Unlike TGF-β1(-/-) mice, the TGF-β1(Lβ3/Lβ3) mice show neither embryonic lethality nor signs of multifocal inflammation, demonstrating that knock-in of the TGF-β3 ligand can prevent the vasculogenesis defects and autoimmunity associated with TGF-β1 deficiency. However, the TGF-β1(Lβ3/Lβ3) mice have a shortened life span and display tooth and bone defects, indicating that the TGF-β homologues are not completely interchangeable. Remarkably, the TGF-β1(Lβ3/Lβ3) mice display an improved metabolic phenotype with reduced body weight gain and enhanced glucose tolerance by induction of beneficial changes to the white adipose tissue compartment. These findings reveal both redundant and unique nonoverlapping functional diversity in TGF-β isoform signaling that has relevance to the design of therapeutics aimed at targeting the TGF-β pathway in human disease.

Intracellular signaling mechanisms associated with CD47 modified surfaces

We have previously established that recombinant CD47 can ameliorate the inflammatory response to synthetic polymeric surfaces. Here, we begin to profile, at the transcriptional, translational and cell signaling level, the inflammatory cell response when blood interacts with CD47 modified polyvinyl chloride (PVC) (CD47-PVC). We used qPCR arrays to compare transcriptional changes between human whole blood exposed to CD47-PVC or PVC. Transcription of IL1F5, IL1F10, IL17F, CCL3, CCL8, CCL28, CXCL12, and CXCL13 was upregulated in blood exposed to PVC, compared to CD47-PVC. The increase in CCL3 and CCL8 transcription correlated with an increase in the chemokines' presence in the plasma. Exposure of blood to CD47-PVC resulted in an increase, compared to PVC, in transcription of CCL2, CCL4, CCL20, CXCL1, TGFβ3, GDF3, GDF10, CD40LG, and TNFSF10. CD47-PVC exposure resulted in an increase of the following matrix metalloproteinase related genes: MMP1, MMP7, MMP13, and MMP16. Phosflow cytometry, and assays examining transcription factor binding, cell attachment, and genome-wide chromatin association indicated that members of the JAK-STAT signaling pathway, particularly JAK2 and STAT5, mediate inflammatory cell interactions with CD47-PVC. Our data demonstrate that differential molecular responses to CD47 involve downregulation of cytokines, upregulation of MMPs, and JAK/STAT signaling mechanisms.

Transforming growth factor Beta-releasing scaffolds for cartilage tissue engineering

The maintenance of a critical threshold concentration of transforming growth factor beta (TGF-β) for a given period of time is crucial for the onset and maintenance of chondrogenesis. Thus, the development of scaffolds that provide temporal and/or spatial control of TGF-β bioavailability has appeal as a mechanism to induce the chondrogenesis of stem cells in vitro and in vivo for articular cartilage repair. In the past decade, many types of scaffolds have been designed to advance this goal: hydrogels based on polysaccharides, hyaluronic acid, and alginate; protein-based hydrogels such as fibrin, gelatin, and collagens; biopolymeric gels and synthetic polymers; and solid and hybrid composite (hydrogel/solid) scaffolds. In this study, we review the progress in developing strategies to deliver TGF-β from scaffolds with the aim of enhancing chondrogenesis. In the future, such scaffolds could prove critical for tissue engineering cartilage, both in vitro and in vivo.

Improvement of human skin cell growth by radiation-induced modifications of a Ge/Ch/Ha scaffold

Gelatin-/chitosan-/hyaluronan-based biomaterials are used in tissue engineering as cell scaffolds. Three gamma radiation doses (1, 10 and 25 kGy) were applied to scaffolds for sterilization. Microstructural changes of the irradiated polymers were evaluated by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). A dose of 25 kGy produced a rough microstructure with a reduction of the porosity (from 99 to 96 %) and pore size (from 160 to 123 μm). Radiation also modified the glass transition temperature between 31.2 and 42.1 °C (1 and 25 kGy respectively). Human skin cells cultivated on scaffolds irradiated with 10 and 25 kGy proliferated at 48 h and secreted transforming growth factor β3 (TGF-β3). Doses of 0 kGy (non-irradiated) or 1 kGy did not stimulate TGF-β3 secretion or cell proliferation. The specific growth rate and lactate production increased proportionally to radiation dose. The use of an appropriate radiation dose improves the cell scaffold properties of biomaterials.

Transforming growth factor-β3 regulates assembly of a non-fibrotic matrix in a 3D corneal model

Corneal tissue engineering has attracted the attention of many researchers over the years, in part due to the cornea's avascularity and relatively straightforward structure. However, the highly organized and structured nature of this optically clear tissue has presented a great challenge. We have previously developed a model in which human corneal fibroblasts (HCFs) are stimulated by a stable vitamin C (VitC) derivative to self-assemble an extracellular matrix (ECM). Addition of TGFβ1 enhanced the assembly of ECM; however, it was accompanied by the upregulation of specific fibrotic markers. In this study, we tested the effects of all three TGFβ isoforms (-β1, -β2 and -β3) on ECM production, as well as expression of fibrotic markers. HCFs were grown in four media conditions for 4 weeks: control, VitC only; T1, VitC + TGFβ1; T2, VitC + TGFβ2; and T3, VitC + TGFβ3. The cultures were analysed with western blots, TEM and indirect immunofluorescence (IF). Compared to controls, all TGFβ isoforms stimulated matrix production by about three-fold. IF showed the presence of type III collagen and smooth muscle actin (SMA) in T1 and T2; however, T3 showed little to no expression. In western blots, T3 stimulated a lower type III:type I collagen ratio when compared to the other conditions. In addition, TEM indicated that T3 stimulated a higher level of matrix alignment and organization. HCFs stimulated by VitC and TGFβ3 appear to generate a matrix that mimics the normal adult or developing human cornea, whereas TGF-β1 and -β2 drive the constructs towards a more fibrotic path.

Continuous supply of TGFβ3 via adenoviral vector promotes type I collagen and viability of fibroblasts in alginate hydrogel

In recent years, transforming growth factor-β3 (TGFβ3) has interested more and more researchers with its competence in engineered histogenesis. In the present study we employed recombinant adenoviral vectors to deliver the constitutively active TGFβ3 gene to human dermal fibroblasts, which could maintain the continuous secretion of TGFβ3 from the cells. The expression of type I collagen in the Ad-TGFβ3 group increased significantly in comparison with other three groups: Neg (cells without treatment of the adenovirus), Ad-null (cells with treatment of the adenovirus, without the inserted gene) and Ad-shRNA (cells with treatment of the adenovirus encoding shRNA specific for type I collagen). Additionally, we demonstrated that TGFβ3 enhanced the expression of Smad4 while inhibiting that of MMP-9, thus promoting the collagen transcription via the Smad signal transduction pathway and restraining collagen degradation by MMP-9, which contributed to the increasing type I collagen expression level. As type I collagen mediates cell-material interactions by providing anchorage, the viability of encapsulated fibroblasts in Ad-TGFβ3 group was significantly higher than that in other three groups. Accordingly, this approach forms an effective way to improve the compatibility of non-adhesive hydrogels containing anchorage-dependent cells.

Chondrogenesis of synovium-derived mesenchymal stem cells in gene-transferred co-culture system

A co-culture strategy has been developed in this study wherein rabbit synovial mesenchymal stem cells (SMSCs) are co-cultured with growth factor (GF) transfected articular chondrocytes. Toward this end, both SMSCs and early passage rabbit articular chondrocytes that had been adenovirally transduced with transforming growth factor-beta 3 (TGF-beta3) gene were separately encapsulated in alginate beads and co-cultured in the same pool of chondrogenic medium. The chondrocytes act as transfected companion cells (TCCs) providing GF supply to induce chondrogenic differentiation of SMSCs that play the role of therapeutic progenitor cells (TPCs). Against the same TCC based TGF-beta3 release profile, the co-culture was started at different time points (Day 0, Day 10 and Day 20) but made to last for identical periods of exposure (30 days) so that the exposure conditions could be optimized in terms of initiation and duration. Transfection of TCCs prevents the stem cell based TPCs from undergoing the invasive procedure. It also prevents unpredictable complications in the TPCs caused by long-term constitutive over-expression of a GF. The adenovirally transfected TCCs exhibit a transient GF expression which results in a timely termination of GF supply to the TPCs. The TCC-sourced transgenic TGF-beta3 successfully induced chondrogenesis in the TPCs. Real-time PCR results show enhanced expression of cartilage markers and immuno/histochemical staining for Glycosaminoglycans (GAG) and Collagen II also shows abundant extracellular matrix (ECM) production and chondrogenic morphogenesis in the co-cultured TPCs. These results confirm the efficacy of directing stem cell differentiation towards chondrogenesis and cartilage tissue formation by co-culturing them with GF transfected chondrocytes.

Repair of chronic osteochondral defects using predifferentiated mesenchymal stem cells in an ovine model

BACKGROUND

The use of mesenchymal stem cells (MSCs) to treat osteochondral defects caused by sports injuries or disease is of particular interest. However, there is a lack of studies in large-animal models examining the benefits of chondrogenic predifferentiation in vitro for repair of chronic osteochondral defects.

HYPOTHESIS

Chondrogenic in vitro predifferentiation of autologous MSCs embedded in a collagen I hydrogel currently in clinical trial use for matrix-associated autologous chondrocyte transplantation facilitates the regeneration of a chronic osteochondral defect in an ovine stifle joint.

STUDY DESIGN

Controlled laboratory study.

METHODS

The optimal predifferentiation period of ovine MSCs within the type I collagen hydrogel in vitro was defined by assessment of several cellular and molecular biological parameters. For the animal study, osteochondral lesions (diameter 7 mm) were created at the medial femoral condyles of the hind legs in 10 merino sheep. To achieve a chronic defect model, implantation of the ovine MSCs/hydrogel constructs was not performed until 6 weeks after defect creation. The 40 defects were divided into 4 treatment groups: (1) chondrogenically predifferentiated ovine MSC/hydrogel constructs (preMSC-gels), (2) undifferentiated ovine MSC/hydrogel constructs (unMSC-gels), (3) cell-free collagen hydrogels (CF-gels), and (4) untreated controls (UCs). Evaluation followed after 6 months.

RESULTS

With regard to proteoglycan content, cell count, gel contraction, apoptosis, compressive properties, and progress of chondrogenic differentiation, a differentiation period of 14 days in vitro was considered optimal. After 6 months in vivo, the defects treated with preMSC-gels showed significantly better histologic scores with morphologic characteristics of hyaline cartilage such as columnarization and presence of collagen type II.

CONCLUSION

Matrix-associated autologous chondrocyte transplantation with predifferentiated MSCs may be a promising approach for repair of focal, chronic osteochondral defects.

CLINICAL RELEVANCE

The results suggest an encouraging method for future treatment of focal osteochondral defects to prevent progression to osteoarthritis.

Human circulating fibrocytes have the capacity to differentiate osteoblasts and chondrocytes

Fibrocytes are bone marrow-derived cells. Fibrocytes can differentiate into adipocyte- and myofibroblast-like cells. Since fibrocytes can behave like mesenchymal progenitor cells, we hypothesized that fibrocytes have the potential to differentiate into other mesenchymal lineage cells, such as osteoblasts and chondrocytes. In this study, we found that fibrocytes differentiated into osteoblast-like cells when cultured in osteogenic media in a manner similar to osteoblast precursor cells. Under these conditions, fibrocytes and osteoblast precursor cells displayed increased calcium deposition, and increased expression of specific osteogenic genes. In addition, dephosphorylation of cAMP-responsive element binding protein was associated with the increased ratio of receptor activator of the NF-kappaB Ligand/osteoprotegerin gene expression and enhanced gene expression of osterix in these cells under these conditions. Both events are important in promoting osteogenesis. In contrast, fibrocytes and mesenchymal stem cells cultured in chondrogenic media in the presence of transforming growth factor-beta3 were found to differentiate to chondrocyte-like cells. Fibrocytes and mesenchymal stem cells under these conditions were found to express increased levels of aggrecan and type II collagen genes. Transcription factor genes associated with chondrogenesis were also found to be induced in fibrocytes and mesenchymal stem cells under these conditions. In contrast, beta-catenin protein and the core binding factor alpha1 subunit protein transcription factor were decreased in expression under these conditions. These data indicate that human fibrocytes have the capability to differentiate into osteoblast- and chondrocyte-like cells. These findings suggest that such cells could be used in cell-based tissue-regenerative therapy.

Concerted stimuli regulating osteo-chondral differentiation from stem cells: phenotype acquisition regulated by microRNAs

Bone and cartilage are being generated de novo through concerted actions of a plethora of signals. These act on stem cells (SCs) recruited for lineage-specific differentiation, with cellular phenotypes representing various functions throughout their life span. The signals are rendered by hormones and growth factors (GFs) and mechanical forces ensuring proper modelling and remodelling of bone and cartilage, due to indigenous and programmed metabolism in SCs, osteoblasts, chondrocytes, as well as osteoclasts and other cell types (eg T helper cells).This review focuses on the concerted action of such signals, as well as the regulatory and/or stabilizing control circuits rendered by a class of small RNAs, designated microRNAs. The impact on cell functions evoked by transcription factors (TFs) via various signalling molecules, also encompassing mechanical stimulation, will be discussed featuring microRNAs as important members of an integrative system. The present approach to cell differentiation in vitro may vastly influence cell engineering for in vivo tissue repair.

TGF-beta3: A potential biological therapy for enhancing chondrogenesis

BACKGROUND

TGF-beta has been proposed to stimulate chondrogenesis through intracellular pathways involving small mothers against decapentaplegic proteins (Smads).

OBJECTIVE

To examine the use of exogenous TGF-beta3 to promote new hyaline cartilage formation.

METHODS

An overview of in vitro and in vivo evidence on the effects of TGF-beta3 on cartilage regeneration.

RESULTS/CONCLUSION

There is robust in vitro evidence suggesting a positive dose- and time-dependent effect of TGF-beta3 on anabolic chondrogenic gene markers such as alpha1-collagen type II and cartilage oligomeric matrix protein in human mesenchymal stem cells. TGF-beta3 cultured with silk elastin-like polymer scaffold carrier exhibits significantly increased glycosaminoglycan and collagen content. In vivo data showed that TGF-beta3 cultured with ovine mesenchymal stem cells in a chitosan scaffold stimulated the growth of hyaline cartilage that was fully integrated into host cartilage tissue of sheep. We highlight the potential for the clinical enhancement of cartilage formation through the use of TGF-beta3 with a suitable dose and scaffold carrier.