Inflammatory bowel disease (IBD), which encompasses Crohn’s disease (CD) and ulcerative colitis (UC), is defined by persistent inflammation of the gastrointestinal system (1). The immune system, the environment, genetics, and gut microbiota all play a role in the onset and progression of IBD (2). The clinical symptoms in patients with IBD include weight loss, abdominal pain, diarrhea, weakness, blood in the stool, urgent bowel movements, and mucus in the stool (3). Since 1990, the incidence has risen in newly industrialized countries in Africa, Asia, and South America, notably Brazil (4). The burden of IBD is predicted to increase by 2050 due to population expansion and ageing, emphasizing how urgent it is to address the changing public health dilemma that IBD poses (5).

An important biological mechanism for all living creatures is cell death (6). In vivo, cell death leads to an inflammatory reaction (7). The ongoing hyperemia, plasma protein leakage, and white blood cell recruitment can be helpful for tissue healing and defense against pathogens (7). This reaction, however, could potentially damage tissue and contribute to the development of certain diseases (7). The emergence of IBDs in both humans and mice has been attributed to cell death mechanisms (8). Apoptosis, pyroptosis, autophagy, ferroptosis, necroptosis, and neutrophil extracellular traps are typical of programmed cell death (PCD) mechanisms (9). These mechanisms are integral to the pathophysiology of IBD, as they lead to intestinal epithelial and immunological cell death (9). Other cell death forms include paraptosis (10), NETosis (11), immunogenic cell death (12), autosis (13), alkaliptosis (14), oxeiptosis (15), erebosis (15), mitoptosis (16), methuosis (17), cuproptosis (18), PANoptosis (19), and entosis (20). Anti-tumor necrosis factor-alpha (TNF-α) medication is a significant breakthrough in IBD treatment, perhaps facilitating mucosal repair by mitigating elevated inflammation-related intestinal epithelial cell (IEC) death (21). On the other hand, some patients either do not react to anti-TNF therapy at all or their response diminishes with time (22). Therefore, comprehending the biology and ramifications of cell death in the intestinal epithelium is essential for developing novel strategies for IBD treatment (21). Furthermore, developing effective medicines to modulate immunological and IEC death pathways can help decrease the growing burden of IBD until 2050.

Mesenchymal stem cells (MSCs) demonstrate a broad range of therapeutic potential in treating IBD (23). MSCs are multipotent stem cells capable of self-renewal and possess various immunomodulatory properties, making them a promising option for treating IBDs (24). The sources of MSCs include dental tissues, menstrual blood, bone marrow, adipose tissue, endometrial polyps, and umbilical cord tissue (25, 26). Researchers have also discovered exosomes in MSCs derived from bone marrow (27, 28), adipose tissue (28, 29), dental pulp (28), menstrual blood (30), and the human umbilical cord (31). According to a recent study, exosomes are significant mediators of MSC function (32). Research shows that MSCs and their exosomes attenuate pyroptosis (31), apoptosis (33), and ferroptosis (34) in dextran sulfate sodium (DSS)-induced IBD. Thus, we review the cell death processes, such as apoptosis, pyroptosis, necroptosis, autophagy, and ferroptosis, and their role in IBD. We also review the potential of MSCs and their extracellular vesicle regulation in cell death to reduce IBD.

Pyroptosis is an inflammatory PCD process triggered by mouse caspase-11, human caspase-4 and 5, or both human and mouse caspase-1 (70). Pyroptosis can be either canonical or noncanonical. The canonical pathway reacts to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) during microbe infection, and the noncanonical pathway reacts to Gram-negative bacteria’s internal lipopolysaccharides (LPS) (71). In both pathways, pyroptosis occurs when inflammatory caspases cleave and activate the pore-forming effector protein gasdermin d (GSDMD) (70).

Canonical inflammasomes are produced by cytosolic pattern-recognition receptors (PRRs) in the presence of pathogen-related signals. This process activates pro-caspase-1 and results in pyroptotic cell death (72). The adaptor protein apoptosis-associated speck-like protein containing CARD (ASC) oligomerizes with inflammasome-forming PRRs, creating a massive cytosol structure that triggers dimerization, autoproteolysis, and pro-caspase-1 zymogen activation (72). A study found that cigarette smoke extracts (CSE) increase NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and caspase-1 activity levels and improve the release of IL-1β and IL-18 in 16 bronchial epithelial cells (73). However, a recent study found that CSE enhances pro-IL-1β expression, activates caspase-1, and releases IL-1β and IL-18 without NLRP3 (74), implying that activation of caspase 1 may either be dependent or independent of NLRP3.

In the noncanonical pathway, Yang and the team found that LPS activation in the cytosol triggers caspase-11-dependent cleavage of the pannexin-1 channel, followed by ATP release, activating the purinergic P2X7 receptor, leading to cytotoxicity. These pathways are essential for initiating endotoxic shock in mice. The study finally found that caspase-11’s noncanonical inflammasome pathway triggers the pannexin-1 channel, leading to K+ efflux and NLRP3 activation (75). In response to microbial infection and cellular injury, the NLRP3 inflammasome plays a crucial role in the innate immune system by mediating caspase-1 activation and the release of proinflammatory cytokines, IL-1β, and IL-18 (76).

Pyroptosis’ final stage requires caspase 1 in the conventional pathway and caspase 4/5/11 (caspase 4/5 in humans, caspase 11 in mice) in the noncanonical pathway to cleave GSDMD at D275 into N- and C-termini. After cleavage, GSDMD’s N-terminus generates a transmembrane pore that leaks cytokines like IL-1β and IL-18 and messes with the water and ion balance, leading to severe inflammation and eventual cell death (71). Figure 2 depicts the mechanism of pyroptosis.

Necroptosis, like other cell deaths such as apoptosis and necrosis, is a caspase-independent PCD mechanism that is believed to be a significant factor in the etiology of various illnesses (99). These include inflammatory conditions of the gut, skin, and lungs, in addition to kidney, heart, and brain ischemia-reperfusion injuries (100). The basic machinery that drives the route consists of the RIPK1 and RIPK3 kinases and the terminal effector pseudokinase mixed lineage kinase domain-like (MLKL), which combine to create cytoplasmic necrosomes, leading to cell enlargement, plasma membrane rupture, intracellular component leakage, and cellular death and inflammation development (101, 102).

The canonical and noncanonical pathways make up this process. In the canonical pathway, it has been shown that RIPK1, RIPK3, and MLKL are the essential components when caspase-8 is deficient or inhibited (103). Necroptosis happens when the caspase activity necessary for apoptosis is inhibited in response to TNF, Fas, or TRAIL, as well as certain toll-like receptor (TLR) ligands (104). The primary mechanism of how necroptosis commences is the liberation of RIPK3 from caspase-8-induced repression (105). Also, Interferon (IFN)-β-induced macrophage necroptosis is triggered by tonic IFN-stimulated gene factor 3 (ISGF3) signaling, resulting in the sustained expression of signal transducer and activator of transcription (STAT)1, STAT2, and interferon regulatory factor 9 (IRF9) (106). Type I (mostly α/β) and type II (γ) IFNs both trigger pro-necrotic signaling through transcriptional activation of the latent kinase PKR that is dependent on Janus kinase (JAK)/STAT (107). Type I and type II IFNs trigger RIPK1/3 kinase-mediated necrosis when caspases (e.g., caspase 8) are inactivated or FADD is deleted or rendered inactive by phosphorylation (107).

The non-canonical route may not require the presence of all the kinases, such as RIPK1/3 and MLKL. For instance, the mouse cytomegalovirus infection results in necrosis that is RIPK3-dependent (108). Another study found that Influenza A virus (IAV) replication triggers Z-RNAs to activate ZBP1 in the nucleus, initiating RIPK3-mediated MLKL activation, leading to nuclear envelope rupture, DNA leakage, and necroptosis (109). Also, ZBP1 triggers RIPK3/MLKL signaling upon detecting cytosolic mitochondrial (mt)DNA (110). A recent study has shown that IAV-induced necroptosis requires RIPK3 in epithelial cells (111). These show that some viral infections may trigger necroptosis without RIPK1. Figure 3 depicts the fundamental machinery in these routes.

Cells use autophagy to break down and recycle proteins and organelles to preserve intracellular homeostasis. Autophagy generally protects cells; nevertheless, excessive autophagic flux or disruption of autophagy pathways typically results in cell death (131).

AMP-activated protein kinase (AMPK), a crucial energy sensor that controls cellular metabolism to preserve energy homeostasis, stimulates autophagy. Nevertheless, the mammalian target of rapamycin (mTOR), a major regulator of cell development that combines signals from growth factors and nutrients, inhibits autophagy (132). AMPK phosphorylates Ser 317 and Ser 777 of unc-51-like kinase 1 (ULK1) in response to a glucose shortage, hence inducing autophagy. High mTOR activity inhibits ULK1 activation when nutrients are sufficient by phosphorylating ULK1 Ser 757 and disrupting the ULK1-AMPK connection (132). Melatonin has been found to inhibit cancer cells by activating autophagy through ULK1 activation, following mTOR inhibition, which phosphorylates Beclin-1. Beclin-1 stimulates autophagy and phosphatidylinositol (3,4,5)-trisphosphate kinase (PI3K) complex I activity in cancer cells in conjunction with autophagy/beclin-1 regulator 1 (AMBRA1) and vacuolar protein sorting 34 (VPS34) (133). These show that AMPK, beclin-1, PI3K, and VPS34 may be involved in autophagy.

The autophagosome, a crucial initial step in autophagy, is a double-membrane organelle that absorbs cytosolic material for degradation. ULK1 mediates this phase by forming a complex with three protein partners: focal adhesion kinase family interacting protein of 200 kDa (FIP200), autophagy-related protein (ATG) 13, and ATG101 (134). During this process, ATG8 is incorporated into the expanding phagophore via covalent attachment to phosphatidylethanolamine via the noncanonical ubiquitin-like conjugation cascade, including the E1 (ATG7), E2 (ATG3, ATG10), and E3 (ATG12-ATG5-ATG16 complex) enzymes (135). A study reveals that the ATG8 conjugation machinery, consisting of six ATG proteins, regulates the shape of the membrane during autophagosome development (136).

A popular marker for macroautophagy tests is LC3. Following translation, ATG4 processes pro-LC3 to reveal the glycine residue at the C-terminus to facilitate downstream conjugation events that convert LC3-I to LC3-II (137). Once autophagosomes fuse with lysosomes, autophagy consumes biological components in double membrane-bound autophagosomes for recycling and clearance (138). Transcription factor EB (TFEB) enhances autophagic flow by promoting lysosome formation, generating autophagosomes, and fusing with lysosomes, thereby aiding in the clearance of harmful protein structures (139). Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), RABs, and tethering complexes (homotypic fusion and protein sorting (HOPS)-tethering complex) are mainly responsible for controlling membrane fusion (140). Figure 4 illustrates the autophagy pathway.

Ferroptosis is a controlled cell death influenced by iron and severe lipid peroxidation (LPO), affecting various physiological and pathological processes (166). An important component of ferroptosis is the transferrin receptor, which is essential for intracellular iron buildup and the development of ferroptosis (167). Iron is typically transported to endosomes by transferrin receptors, where the six-transmembrane epithelial antigen of prostate family member 3 (STEAP3) converts it from Fe3+ to Fe2+ (168). The plasmalemma divalent metal ion transporter 1 (DMT1) facilitates the cellular uptake of Fe2+, while transferrin receptors carry transferrin-bound Fe3+ (169). Through poly r(C)-binding protein 1 (PCBP1), the labile iron pool (LIP) is coordinated, allowing the cell to effectively transport iron to non-heme iron enzymes, store iron in ferritin, and provide iron for the Fe-S cluster assembly/repair mechanism (170). Ferroportin (FPN), the only known iron exporter, is crucial for maintaining iron homeostasis (171). Ferritin is transported to autophagolysosomes for breakdown by nuclear receptor coactivator 4 during ferritinophagy (172). After autophagy degrades ferritin, iron ions are released, which trigger the LIP to initiate the fenton reaction, leading to lipid peroxidation (172). A study reveals that Z-Ligustilide’s excessive activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway is responsible for the selective onset of ferroptosis in leukemia cells. The primary cause is the ROS-induced accumulation of LIP in acute myeloid leukemia cells (173).

An intracellular antioxidant called glutathione (GSH) is produced from glutamate, cysteine, and glycine (174). Free cystine enters cells via the cystine-glutamate antiporter xCT, while plasma glutathione-disulphide may be the main source of cystine throughout the body (175). A study in acute myeloid cells found that reduced cystine and glutamine levels disrupt GSH synthesis, leading to the malfunction of glutathione peroxidase-4 (GPX4), a co-factor used to maintain lipid peroxidation homeostasis (176). Small compounds that inhibit GPX4 generate a fatal buildup of lipid peroxides and promote ferroptosis cell death (177). A study by Cheng and the team found that Leonurine raises GPX4 and GSH, fixes ultrastructural defects in mitochondria effectively, and greatly lowers ferroptosis in acute kidney injury (AKI), both in vivo and in vitro. It also considerably reduces endoplasmic reticulum (ER) stress by downregulating activating transcription factor 4 (ATF4), CHOP, and Chac glutathione-specific γ−glutamylcyclotransferase 1 (CHAC1) (178). This may imply that in ER stress, the upregulation of ATF4, CHOP, and CHAC1 may suppress GSH and GPX4, leading to ferroptosis. Another study found that the GSH/glutathione disulphide ratio decreases when cells are exposed to dihydroartemisinin (DHA), a ferroptosis inducer. Treatment with DHA also inhibits GPX4 and increases CHAC1 expression levels (179). Lipid peroxidation, which may result from GPX4 activity suppression, can cause ferroptosis (180).

The long-chain acyl-coenzyme A synthase 4 (ACSL4) esterifies coenzyme A (CoA) to produce certain polyunsaturated fatty acids (PUFAs), including adrenic and arachidonic acid. The production of arachidonoyl-CoA, facilitated by ACSL4, plays a crucial role in ferroptosis execution by promoting phospholipid peroxidation (181). TPCI (photosensitizer) produces ROS when exposed to light, activating ALOX12 or resuscitating it through SLC7A11 downregulation. This leads to direct peroxidation of PUFAs into fatal lipid ROS, causing ferroptosis in cancer cells independent of ACSL4 (182). The study suggests lipid peroxidation may occur through arachidonate 12-lipoxygenase (ALOX12) activation when solute carrier family (SLC) 7A11 is down-regulated without ACSL4.

Recent research has revealed a connection between ferroptosis and p53 (183). Ren and colleagues found that the p53/spermidine/spermine N1-acetyltransferase 1 (SAT1)/arachidonic acid 15-lipoxygenase (ALOX15) signaling pathway induces ferroptosis, which is significantly suppressed by cerebroprotein hydrolysate-I in Alzheimer’s disease (184). The expression of SAT1 causes LPO and makes cells more susceptible to ferroptosis in response to stress caused by ROS. In xenograft tumor models, this results in tumor growth inhibition (185). However, in xenograft mouse models, inhibiting endogenous independent phospholipase A2β (iPLA2β) causes tumor cells to undergo p53-driven ferroptosis, increasing p53-dependent tumor suppression (186). This implies that the activation of iPLA2β may prevent p53-driven ferroptosis.

Certain elements have been found to trigger lipid peroxidation, leading to ferroptosis. Like erastin and RSL3, which block system XC- or directly target the reducing enzyme GPX4, respectively, FINO2 does not deplete GPX4 protein, unlike FIN56. Rather, FINO2 directly oxidizes iron and indirectly inhibits GPX4’s enzymatic activity, leading to widespread lipid peroxidation (187). However, GTP cyclohydrolase-1 (GCH1)-expressing cells synthesize tetrahydrobiopterin (BH4)/dihydrobiopterin (BH2), which results in lipid remodeling and inhibits ferroptosis by blocking phospholipid loss with two acyl tails of polyunsaturated fats (188). BH4 is a strong antioxidant that sequesters radicals and, either by itself or in combination with vitamin E, prevents lipid membranes from undergoing autoxidation (189).The transsulfuration pathway, mevalonate pathway, ferroptosis inhibitory protein 1 (FSP1)-coenzyme Q10 (CoQ10) pathway, dihydroorotate dehydrogenase (DHODH)-dihydroubiquione (CoQH2) pathway, and GTP cyclohydrolase-1 (GCH1)-tetrahydrobiopterin (BH4) pathway are among the other antioxidant systems that have also been linked to the regulation of ferroptosis (190) ( Figure 5 ).

IEC passive shedding largely involves apoptosis at villi tips (218). In mice, shed IECs have been shown to persist for several hours, promoting the expression of antimicrobial genes at the tips of villi and helping to control the makeup of the gut microbiota (219).The rate of senescent epithelial monolayer cell clearance and the growth of stem cells in the crypts are both correlated with the shedding and renewal of IECs (21). It is unclear exactly how IEC death occurs in IBD (21). However, IEC shedding is elevated, and barrier integrity is compromised in the intestinal lamina propria due to a highly inflammatory environment rich in the proinflammatory cytokine TNF-α, which further fuels inflammation (21). Also, in IBD, IECs are continuously lost, and other immune cells are also continuously shed; this is most noticeable during the active stages of the disease. In IBD, the digestive tract experiences excessive cell death as a result of ongoing inflammation and recurring bouts. Increased cell death may stimulate the gut immune system, exacerbating intestinal inflammation in IBD (220, 221). Excessive IEC apoptotic cell death during the pathophysiological state causes a chronic inflammatory condition (222). Later, the necroptotic cell death takes over, bringing about more pathological features than apoptosis (222). It may also trigger other lytic cell death mechanisms, such as ferroptosis and pyroptosis, to increase the pathogenesis of intestinal diseases (222).These findings suggest that excessive cell death may destabilize the barrier and activate immune cells, resulting in additional inflammation. The commencement of apoptotic cell death may trigger the activation of other cell death mechanisms such as necroptosis, ferroptosis, and pyroptosis. As a result, cell death in IBD may activate other cell death processes, and in the presence of an inflammatory environment, the vicious cycle of cell death persists.

IBD-related necroptosis mostly affects IECs, and RIPK3 inhibition can somewhat reduce the chronic intestinal inflammation brought on by necroptosis (223, 224). In IBD, intestinal stem cells may also undergo necroptosis. The loss of the essential gene SETDB1 can cause necroptosis, which alters colon epithelial differentiation, compromises the mucosal layer, and increases intestinal inflammation (225, 226). According to a study on IBD patients, RIPK3-induced necroptosis modifies occludin, zonulin-1, and E-cadherin, which impacts membrane permeability (120). In the IBD gut, cell pyroptosis is caused by inflammasome activation (e.g., NLRP3), essential for innate immune reactions, and is vital for gut-brain balance and gut microbiota maintenance (227, 228). Cell pyroptosis, which is mostly carried out by proteins like GSDMB, GADMD, and GSDME, mediates several damage signals that result in chronic inflammation that persists in IBD (229). Additionally, GSDMB, a pyroptosis executor, is essential for preserving the function of the epithelial layer and reducing inflammation in IBD (230). Necroptosis and pyroptosis can cause lytic cell death, which is probably why they have the potential to spread disease. Distinct from apoptosis, this type of cell suicide permits the release of immunogenic cellular material, such as inflammatory cytokines like interleukin-1β (IL-1β) and damage-associated molecular patterns (DAMPs), to cause inflammation (231). Ferroptosis is seen in IECs of DSS animals and IBD patients, mostly due to endoplasmic reticulum stress and the NF-κB pathway (232). In IBD, the intestinal epithelium experiences excessive lipid peroxidation, elevated ferrous iron levels, and ROS buildup, contributing to chronic aberrant inflammation (232, 233). Ferroptosis inhibitors have demonstrated efficacious management of intestinal chronic inflammation, a finding extensively confirmed in both animal model and IBD patients (211, 234, 235).

Intestinal homeostasis and repair depend on autophagy and its regulatory mechanisms, promoting intestinal barrier function in response to cellular stress by regulating tight junctions and preventing cell death. Moreover, it has become evident that autophagy plays a part in intestinal stem cells as well as secretory cells, influencing their metabolism as well as their ability to proliferate and regenerate (236).

In addition, TNF-α can cause RIPK3-dependent necroptosis and extrinsic caspase-8 and executioner caspase-3-dependent apoptosis when caspase-8 or TNFAIP3 (A20, a ubiquitin editing enzyme) capabilities are compromised (223, 237–241). TNF-α can also cause IEC shedding (242–245). Unlike homeostatic IEC shedding where barrier integrity is maintained by rapid basolateral tight-junction protein redistribution and zipper-like replacement by neighboring cells (246, 247), necroptosis, in which several nearby IECs lose contact, has been documented to accompany TNF-α-induced shedding (243, 248). It would be challenging to discern cause from effect if greater IEC death and barrier integrity resulted in more inflammation, intestinal epithelial damage, and possibly even dysbiosis (21). Additional elements that might cause cell death include oxidative stress, hypoxia, and endoplasmic reticulum (ER) stress (249). Cell death can result in aberrant IECs, which attract immune cells and promote inflammation. At the same time, inflammatory cytokines like TNF can trigger cell death, which leads to IEC abnormalities. As a result, cell death is bidirectional, making it difficult to discern the causal link between cell death and inflammation.

As previously documented, IEC cell death leads to IEC irregularity, which attracts immune cells and promotes inflammation. Meanwhile, inflammatory cytokines such as TNF-α can cause cell death, resulting in IEC abnormality. Therefore, cell death is a bidirectional process, and it may be difficult to determine the causal relationship between cell death and inflammation. Therapies targeting the upstream cytokines such as TNF-α and IL-1β may be the best option for treating cell death, which can help reduce cell death at the IEC or immune cells. This may prevent proapoptotic signals. It is also known that excessive IEC apoptotic cell death leads to chronic inflammation, followed by necroptotic cell death. This causes more pathological features and potentially triggers other lytic cell death mechanisms like ferroptosis and pyroptosis, increasing the pathogenesis of intestinal diseases. Therefore, preventing the upstream signal TNF-α may prevent cell death. Some patients may not react to anti-TNF therapy or experience diminishing response over time. Targeting cell death markers with MSCs may prevent cell death, gut abnormalities, and inflammation, which may prevent further cell death processes. Therefore, exploring combination therapy with IBD medications and MSCs is recommended for better therapeutic outcomes.

MSCs are a crucial alternative for tissue healing due to their differentiation capacity and paracrine characteristics. MSCs release extracellular vesicles (exosomes and microvesicles) and secrete soluble substances, fulfilling their paracrine roles. Extracellular vesicles, primarily endosomal in origin, carry proteins, mRNA, and miRNA from the cells of origin to target cells. Recent research indicates that MSCs’ therapeutic impact in animal disease models is solely due to these extracellular vesicles, suggesting they could replace MSC-based therapy in regenerative medicine (250). Nearly every tissue contains MSCs, which develop into specific cell types and perform immunomodulatory actions (251). MSCs primarily engage in immunomodulatory activities through cell-to-cell interactions with immune cells, including T cells, B cells, natural killer (NK) cells, macrophages, monocytes, dendritic cells (DCs), and neutrophils (252). Therefore, MSCs may regulate cell death through their extracellular vesicles (EVs) and interactions with immune cells. Major cell death markers in IBD lead to greater epithelial cell loss, decreased intestinal barrier integrity, and increased inflammatory cytokines and alarmins. DSS, 2,4,6-trinitrobenzene sulfonic acid (TNBS), and LPS have been utilized to create cell death models in tissues and cells. MSCs’ ability to regulate these markers, prevent epithelial cell loss, improve intestinal barrier integrity, and reduce inflammation may help prevent IBD. These will promote cell survival, tissue regeneration, immune cell modulation, and reduce inflammation.

The lack of confidence in MSC therapy stems from inconsistent pre-clinical and clinical outcomes and the mismatch between predicted and actual efficacy in various illnesses (332). Beyond safety, clinical effectiveness remains very diverse and contentious, with no evidence of a molecular explanation and conflicting therapeutic advantages (333). For instance, several clinical trials on MSC treatments in IBD (CD) reported fever (293), anal abscess and proctalgia (303), worsening of CD, diarrhea, increased blood bilirubin (305), and anal abscess/fistula (304). The trials suggest that while MSCs are safe and effective, their adverse effects may pose practical challenges. Interestingly, one study identified a major adverse event (2 dysplasia-related lesions) (299). Nonetheless, the study stated that MSCs most likely did not cause this. Research has indicated that MSCs might encourage the growth of tumors. For instance, the proangiogenic factors released by cancer cells to promote angiogenesis and tumor development may be enriched by IL-6 produced by MSCs; addressing this relationship may result in new preventative and therapeutic approaches (334). IL-6, secreted by MSCs, stimulates the growth of colorectal tumor-initiating cells and encourages tumor development through STAT3 signaling (335). In a different investigation, MSCs improved the capacity of lung cancer cells A549 and CL1–5 to grow tumors in immunocompromised mice (336). Another study has also demonstrated that MSC treatment has a protective effect on tumor development. For instance, Hu and colleagues discovered that late administration of MSCs promotes colitis-associated cancer (CAC) development, while early administration prevents CAC incidence (337). On the contrary, issues with EVs, the mediators of MSCs, have yet to be reported in IBD. As a result, further clinical studies with EVs should be considered. EVs, the mediators of MSCs, could be the new era of treating IBD-associated cell death.

Several limitations have been identified with the use of MSCs. Disease results vary significantly depending on the type of mesenchymal cells used, how the cells are preconditioned, how often treatments are administered, and how they are administered. Thus, a more thorough study of MSCs is required (255). According to the review, different MSC sources and conditioning methods are employed, which may influence the result of the MSCs. For instance, Nishikawa and colleagues found that while cell-free lysate injection produced a comparable improvement to the previously documented MSC treatment, the mechanism by which pleiotropic factors ameliorate DSS-induced colitis remains unknown. Also, what precisely makes up FADSTL and the process that underlies their apparent effectiveness is uncertain. Further research is needed to comprehend the mechanisms behind its anti-inflammatory and anti-apoptotic properties (253). Another study found that the mechanism of miR-378a-5p controlling NLRP3 is non-specific, highlighting the need for more research to gain clarification (31).

MSCs and their mediators have been shown to regulate cell death pathways in various diseases, including IBD. MSCs alleviate barrier defects and decrease immune cell infiltrations and inflammatory cytokine release. However, side effects may pose challenges in clinical settings. Clinical investigations show insufficient evidence to relate EVs to cell death in IBD, and EV use has not been associated with any preclinical negative effects. The diversity of extracellular vesicles (EVs) (338, 339) and the minimal uniformity regarding the methodologies for their isolation, purification, and characterization (340) make the application of EVs in the clinical setting challenging. Additionally, the wide range of methods utilizing unique biochemical characteristics of EVs and the lack of standardized protocols make data interpretation extremely challenging (341). The review’s findings showed evidence that may impede clinical research using EVs in IBD. For instance, regarding the appropriate dosage for EV use, different research studies have used varying amounts of EVs in colitis treatment; hence, there is no standardized dose when translating to clinical trials involving humans. Additionally, colitis induction to mimic the human model is created using different concentrations, making standardization of this model with EV treatment challenging for clinical studies. Frequent injections with EVs in animal models may also pose a challenge during clinical studies. Using different animal species for colitis model, different sources of EVs, and frequency of administration of EVs may also affect translation to clinical settings. Although these preclinical studies have shown the potential to explore the modulatory mechanism of EVs in IBD, the complete understanding of the mechanism in human IBD is lacking, therefore a study suggested the exploration of EVs in human model to better understand its mechanism (287). Notwithstanding these difficulties, EVs might one day be used to diagnose IBD, as is the case with CRC (342), given that IBD is a risk factor for CRC. Studies should focus on the standardization of protocols and the uniformity of EV extraction for IBD experiments, other routes of EV administration (oral) should be explored, and efforts to research larger sample sizes in clinical studies should be encouraged. Preclinical and clinical research should focus on MSCS and other cell death mechanisms with less evidence, such as cuproptosis. Cuproptosis, a type of cell death involving copper ions being delivered to lipoylated TCA cycle proteins, is a widely researched topic in cancer research. However, it is also linked to harmful processes like oxidative stress, apoptosis, and inflammation (343, 344). Studies have also shown that cuproptosis genes may serve as biomarkers for IBD, and these genes have been associated with immune cell infiltration regulation in IBD (345–347). Nevertheless, the direct mechanism of MSCs targeting cuproptosis is novel and needs further exploration since cuproptosis may be implicated in the pathogenesis of IBD. Moreover, as cuproptosis represents a novel form of cellular death and has been insufficiently studied, further research will enhance the limited understanding of cuproptosis, offer innovative therapeutic strategies, elucidate disease variations, and furnish methodologies for assessing and identifying cell death pathways. Further exploration of MSCs and exosomes with other IBD medicines in cell death is warranted.