Periodontitis is primarily a chronic infectious disease of periodontal tissues caused by plaque biofilm and is a risk factor for various systemic diseases, such as diabetes mellitus, cardiovascular complications, Alzheimer’s disease, tumors, etc [1]. (Fig. 1).

Fig. 1

Schematics of systemic diseases that are closely related to periodontitis

Conventional treatment strategies fail to achieve periodontal support structure regeneration [2]. Recent insights into cell-based therapeutics may play an important role in the realization of robust and efficient periodontal regeneration [3].

Mesenchymal stem cells (MSCs) have emerged as the most extensively researched and applied stem cells in regenerative medicine [4]. Their therapeutic potential can be attributed to cell homing, promotion of cell differentiation, and secretion of bioactive factors [5, 6]. Actually, most of the stem cells which transmigrate to the focus of injury were sacrificed due to limited homing and poor survival [7]. Recent studies have brought attention to the wide array of bioactive components of MSCs [8]. In this process, microRNAs (miRNAs) constitute an important fraction of MSCs content have attracted much attention for its potential use in tissue repair and regeneration [9, 10]. MiRNAs are small non-coding RNAs that regulate gene expression [11] by binding to complementary sites on target genes and mediating post-transcriptional gene silencing [12]. Interestingly, the expression of miRNAs in cells are specific, and their changes in response to fluctuations in physiological states or pathological conditions [13,14,15]. In addition, miRNAs encapsulated in MSCs-secreted exosomes, acting as mediators of intercellular signaling, regulating effector cell functions, and ameliorating inflammatory reactions [16].

Both miRNAs may be capable of independently triggering regeneration and repair, as well as encouraging angiogenesis and cell proliferation, regulating autophagy, and reducing apoptosis, while mediating inflammation in periodontitis [17,18,19,20].

In recent years, substantial studies found the relationship between MSCs-derived miRNAs and periodontitis, yet there is considerable heterogeneity among the studied miRNAs. The objective of this review was to identify and summarize a set of microRNAs which express specifically in MSCs can be used as targets in periodontal diseases, to refine the expression patterns with respect to specific cell and to examine their roles in mechanistic studies, and to determine which of them show the precise therapeutic performance for periodontal regeneration.

Mesenchymal stem cell-derived miRNAs in periodontal tissue regeneration

We observed that miRNAs are versatile and stable, capable of existing as either intracellular or extracellular entities [21], which can be found partly encapsulated in MSCs-secreted exosomes [22]. The sources, expression levels, regulatory functions, and mechanisms of action show significant differences between these two forms: [23] exosomal miRNAs which are released from cells into microenvironment are generally less concentrated than their intracellular counterparts, and current high-throughput sequencing technologies are able to detect these variations [24, 25] (Fig. 2).

Fig. 2

Multi-omics approaches to predict differentially expressed miRNAs and their downstream targets

However, little is known about how and what determines the miRNA content of extracellular vesicles (EVs) from MSCs, which is a critical issue for further therapeutic applications [26].Furthermore, MSCs-derived exosomes provide considerable stability to the miRNAs they carry, protecting them from enzymatic degradation and facilitating delivery to recipient cells through various pathways [27]. Additionally, while intracellular miRNAs are produced through their own transcription and processing [28], miRNAs in exosomes primarily originate from the secretion and release of intracellular miRNAs [29]. Importantly, the regulatory effects of miRNAs are heavily influenced by their cellular location. Endogenous miRNAs regulate intracellular gene expression and influence the physiopathological activities of the cells in which they are located [30]. Conversely, exosomal miRNAs do not degrade after delivery into cells and can act as cellular messengers to impact a more diverse set of recipient cells [31].

Intracellular miRNAs within MSCs

Intracellular miRNAs are produced by two RNase III proteins, Drosha and Dicer [32].

In the following sections, we briefly discuss a few selective and prevalent miRNAs within MSCs [33]. (Table 1). Importantly, we focus primarily on functions of these miRNAs associated with periodontal regeneration that were shown to be differentially expressed in MSCs in the recent studies (Fig. 3).

Table 1 Intracellular miRNAs from MSCs in periodontal regenerationFig. 3

Schematics of mechanisms that MSCs-derived miRNAs promote periodontal regeneration on cell migration and differentiation, angiogenesis of periodontal tissues, regulating autophagy and anti-apoptotic anti-inflammatory. A. MiRNAs suppress inflammatory cell migration to the injury site and promote repairable cell proliferation and differentiation. b. MiRNAs promote bone regeneration by interacting with target cells, including osteoblasts and osteoclasts. c. Angiogenesis is also closely associated with regeneration. D. MiRNAs control pro-inflammatory and anti-inflammatory responses in the periodontal microenvironment. E. MiRNAs regulate autophagy and apoptosis

MiR-31 exerts a regulatory influence on the osteogenic differentiation of MSCs. MiR-31 and Osterix inversely correlate during osteogenic differentiation. The expression of miR-31 in bone marrow stem cells (BMSCs) increases interacting with the Osterix (SP7), bone-specific transcription factor, which is essential for controlling osteoblast maturation and bone formation [34]. Suppression of Osterix levels enhances alkaline phosphatase activity and the deposition of mineralized nodules, demonstrating the role of miR-31 in the regulation of osteogenic differentiation and mineralization of bone marrow stem cells (BMSCs) [35]. Moreover, miR-31 expression is significantly lower in periodontitis gingival tissue compared to healthy gingival, which can result in suppression of osteogenesis process and the progression of bone resorption [36].

MiR-132 is downregulated during the osteogenic differentiation of Periodontal ligament stem cells (PDLSCs), which are pivotal in maintaining the stability of the periodontal ligament, repairing osteochondral tissue damage, and enhancing cellular renewal and function, rendering them ideal for periodontal tissue regeneration [37].In other words, miR-132 overexpression inhibits PDLSCs osteogenesis. Xu et al. found that the mRNA and protein levels of ALP, BMP2, Runx2, and OCN in PDLSCs decreased substantially by targeting growth differentiation factor 5(GDF5) and activating the NF-κB axis. The intersection of miR-132, GDF5, and NF-κB regulates osteogenic differentiation of PLDSCs [38].

MiR-589-3p was identified as the most upregulated miRNA in osteogenic induction and non-induction of PDLSCs. The expression of miR-583-3p was notably increased in PDLSCs during osteogenic induction, enhancing the osteogenic capacity of PDLSCs along with increases in ALP activity, matrix mineralization, and RUNX2, OCN, and OSX expression. Bioinformatics analysis and luciferase activity assays showed that miR-589-3p directly targeted ATF1 to promote the proliferation and osteogenic differentiation of PDLSCs [39].

MiR-21 has been previously reported to be highly expressed in many tumor cells, associated with tumor progression [40]. Recently several studies have highlighted is also predominantly found in mesenchymal stem cells and plays a crucial role in tissue regeneration: miR-21 overexpression in human umbilical cord blood-derived mesenchymal stem cells (HUCBMSCs) promotes angiogenesis by enhancing hypoxia-inducible factor-1α (HIF-1α) activity [41]. Additionally, rising miR-21 can markedly enhanced osteogenic differentiation in bone marrow stem cells (BMSCs) via the PTEN/PI3K/Akt/HIF-1α pathway [43]. During osteogenic differentiation of PDLSCs, the expression level of miR-21 is reduced. Molecular mechanism has shown that it targets to Smad5 and stimulates the Smad5-Runx2 signaling pathway, suppresses the expression of osteogenic-related genes, and inhibits osteogenic differentiation in PDLSCs miR-21 [42].Therefore, these studies investigated the function of miR-21 in MSCs, which could provide clues to increase our understanding of altering the expression of intracellular miRNAs in various cells or control several gene regulatory networks may have opposite effects on periodontal tissue regeneration [69]. Furthermore, the expression and regulatory functions of miRNAs differ under various environmental conditions: miR-21 is expressed at elevated levels in mechanically stretched PDLSCs compared to untreated cells. In vitro, mechanical force-induced stimulation alters bone remodeling homeostasis, and miR-21 directly regulates ACVR2B—a key regulator of osteogenic differentiation—thereby enhancing osteogenic differentiation in stretched PDLSCs [70]. Wu et al. reported that miR-21 also modulates the immune microenvironment and influences MSCs regeneration by downregulating transforming growth factor-β1 (TGF-β1) [71].

Cytokine stimulation leads to significant alterations in the expression profiles of miRNAs and transcription factors in mesenchymal stem cells [72]. Research has shown that periodontal regenerative cytokines treatment such as FGF2, BDNF, BMP2 suppresses the expression of miR-628-5p in Human MSCs (HMSCs), highlighting miR-628-5p as a key miRNA in the periodontal regeneration process. MiR-628-5p adversely affects the stemness of MSCs relevant to periodontal regeneration. Specifically, miR-628-5p facilitates the osteogenic process in MSCs by suppressing the upregulation of ETV1, GATA6, and SOX11, thereby enhancing periodontal regeneration. Overexpression of miR-628-5p also influences the expression of related transcription factors and reduces the proliferative capacity of tissue cells [59].

Extracellular miRNAs within exosomes

The role of stem cells in tissue regeneration does not depend completely on direct proliferation and differentiation of MSCs at the site of injury, but also plays an important role in paracrine action, in which bioactive substances can diffuse to neighboring cells through the intercellular space, participate in cell-to-cell communication, and affect the biological functions of tissue cells [73].

Therefore, exosomes are extracellular vesicles secreted by MSCs which carries bioactive molecules including proteins, nucleic acids, and lipids, being envisioned as a new and attractive source of MSCs for tissue engineering [74] (Fig. 4).

Fig. 4

The biogenesis and components of extracellular vesicles (EVs) in MSCs

As a key component of MSCs-EVs, miRNAs are shown to have promising regenerative properties to periodontitis [75]. Consequently, several studies have been described miRNAs highly enriched in exosomes to explore the potential effect and mechanisms of exosomal miRNAs (Table 2), functions of these miRNAs will be specifically submitted below.

Table 2 Specific miRNAs in MSCs-EVs with reported roles in periodontal regeneration

MiR-22-3p from BMSCs-derived EVs has been reported to be associated with osteogenic differentiation, which negatively targets fat mass and obesity-associated proteins (FTO). FTO influences adipogenesis and osteogenesis of stem cell [76]. Repressing the expression of FTO, which reduces MYC mRNA stability and suppresses the MYC pathway, which interacts with PI3K activation, resulting in inhibition of the PI3K/AKT pathway to enhance osteogenic differentiation with increased ALP activity and expression of genes related to mineralization [77].

Following tumor necrosis factor (TNF-α) stimulation, exosomes from human gingival mesenchymal stem cells (GMSCs) play a crucial role in preventing alveolar bone loss and are now attributed to TNFα-inducible exosomal miR-1260b. Research indicates that miR-1260b binds to transcription factor (ATF)-6β, which regulates osteoclastogenesis under endoplasmic reticulum (ER) stress, inhibits RANKL expression, and prevents periodontal bone loss [21]. Moreover, miR-1260b in TNF-α-induced exosomes is suggested to drive macrophage polarization towards the M2 phenotype, alleviate inflammation, and enhance periodontal tissue repair and regeneration in mice [78].

The regenerative properties of exosomes derived from PDLSCs are likely due to variations in miRNA expression profiles of PDLSCs-EVs [79]. In exosomes from PDLSCs in osteogenesis, and 72 miRNAs were upregulated and 35 were downregulated compared to those from undifferentiated PDLSCs. The sequencing results revealed that miR-122-5p, miR-142-5p, miR-25-3p, and miR-192-5p were notably upregulated in exosomes from PDLSCs during osteogenic differentiation. These miRNAs act as osteogenic regulators, enhancing osteogenesis-related signaling pathways and promoting periodontal bone regeneration by regulating their downstream target genes and pathways [80].

MiR-155-5p is critical for regulating the differentiation and homeostasis of T-helper 17 (Th17) and regulatory T (Treg) cells. Exosomes isolated from normal PDLSCs exhibit decreased miR-155-5p expression compared to those isolated from periodontal stem cells stimulated with LPS, which induces and imitates a localized inflammatory microenvironment. Inhibition of miR-155-5p results in a decrease in Treg levels, an increase in Th17 levels, and reduced inflammation. Sirtuin-1 (SIRT1) is a direct target of miR-155‐5p. Thus, lowering miR-155-5p expression can diminish inflammation and prevent the progression of periodontitis through the Th17/Treg/miRNA-155-5p/ /SIRT1 signaling pathway [81].

This evidence indicates that MSCs-derived exosomal miRNAs are valuable signaling molecules that can contribute to strengthening the significance of the role of exosomes. Because the link between miRNA profiles in exosomes and periodontitis is very strong, exosomal miRNA expression is under investigation as a biomarker for periodontal regeneration.

Mechanisms of mesenchymal stem cell-derived miRNAs in periodontal tissue regeneration

Several studies have indicated that the therapeutic effects of stem cells are partly derived from the presence of miRNAs [82, 83]. The discovery of stem cell-derived miRNAs can be seen as a brand-new lantern that sheds light on novel therapeutic approaches for periodontal regeneration. Therefore, more insight into the underlying mechanisms of these therapies is needed to enhance the efficacy of the established miRNAs-based therapies. Recently, several studies have been conducted on the underlying mechanisms (Fig. 3), which are specifically explained below (Tables 1 and 2).

Regulating bone formation of periodontal tissues

In recent years, advances in bone tissue engineering have offered new hope for the repair and regeneration of alveolar bones in patients with periodontitis. Analysis of MSCs properties that contribute to the enhancement of osteogenesis reiterates the importance of miRNAs [84]. A recent study reported that significant differences in miRNA expression profiles are key mechanisms regulating osteogenic differentiation [13] (Fig. 5).

Fig. 5

Schematic illustration of periodontitis treatment by altering MSCs-derived miRNA expression level to contribute to the improvement of stem cell therapy. (All images are reproduced with permission from Zhang et al. [13])

The expression of miR-26a is significantly increased in both BMSCs and ADSCs during osteogenic induction [97], but shows a completely opposite effect on osteogenic differentiation. Overexpression of miR-26a strengthened the osteogenic differentiation of BMSCs, whereas osteogenesis was significantly inhibited in the ADSCs. This phenomenon is most likely due to miR-26a depending on Wnt and BMP signaling to show different functions in different types of cells [98]. Thus, the involvement of miR-26a-enriched BMSCs can be used to significantly promote osteogenesis in periodontal tissues [99].

Additionally, numerous studies on miRNAs have demonstrated that specific miRNA that can be selectively packaged into EVs negatively modulate osteogenesis in proximal or distal cells.

MiR-765 decreases in hMSCs during osteogenic differentiation. Overexpression of miR-765 downregulates osteogenesis-related genes, ALP activity, and matrix mineralization. MiR-765 acts to negatively regulates osteogenic differentiation of hMSCs by directly binding to BMP6, which is associated with bone formation. BMP6 ultimately activates Smad1/5/9. This suggests that the BMP6/Smad1/5/9 pathway is likely to be a key regulatory mechanism in the context of hMSC osteogenic differentiation [100]. It is discovered that 13 miRNAs promoted and 17 suppressed odontogenic/osteogenic differentiation: hsa-miR-140-5p, hsa-miR-218 and hsa-miR-143 were the most intensely reported miRNAs which restrain the proliferation and osteoblastic differentiation of Human dental pulp-derived mesenchymal stem cells (hDP-MSCs). This miRNA group is critical for osteoblast differentiation and regulates progression of the osteogenic spectrum [101].

Promoting the angiogenesis of MSCs

Periodontitis is invariably associated with abnormal angiogenesis which can sustain or strengthen inflammation [