1 Introduction

In the evolving landscape of cancer therapy, stem cell-based treatments have emerged as a promising treatment of the proliferation and metastasis of cancer cells. Stem cells, with their inherent ability to differentiate and regenerate, offer a unique mechanism for targeting cancerous cells and enhancing the efficacy of traditional therapeutic modalities. Despite significant advances in medical treatments, cancer continues to be a leading cause of mortality worldwide, with an estimated 19.3 million new cases and 10 million cancer-related deaths in 2020 alone [1].This global burden underscores the critical need for innovative therapeutic strategies. Common cancer treatment methods include surgery, chemotherapy, radiation therapy, immunotherapy, and targeted therapy, each with varying degrees of success and side effects. Stem cells have shown considerable promise in oncological applications, primarily due to their ability to inhibit tumor growth and support the regenerative processes of damaged tissues during chemotherapy and radiation. Stem cell therapy involves using stem cells to replace or repair damaged cells within the body, and in the context of cancer, this can mean using stem cells to enhance the body’s natural ability to combat cancer or to repair tissues damaged by conventional treatments. This multifaceted approach not only targets cancer cells but also aims to improve the overall resilience and recovery of patients undergoing cancer treatment.

However, a comprehensive understanding of the differential impacts of various stem cell types on cancer remains underexplored. The intricate interplay between stem cells and cancer offers significant promise in revolutionizing oncology treatment approaches. This paper aims to comprehensively examine the diverse functions of various stem cell types, with a specific emphasis on elucidating the suppressive effects demonstrated by human umbilical cord mesenchymal stem cells (HUCMSCs) and mesenchymal stem cells (MSCs) in cancer therapy. The primary objective of this study is to uncover the intricate mechanisms through which stem cells exert their therapeutic efficacy and to delineate the potential clinical implications of utilizing these cellular entities in combatting cancer cells. Through a comprehensive literature review and analysis of relevant theories, this article endeavors to synthesize current knowledge and identify pivotal insights regarding the role of stem cells in cancer treatment. This research holds profound implications for consolidating and advancing people‘s understanding of stem cell therapies in oncology. By elucidating the mechanisms by which stem cells exert their suppressive effects on cancer cells, this study has the potential to inform the development of novel therapeutic strategies that target the underlying biology of cancer.

2 Overview of the pathogenesis of cancer

Cancer is fundamentally a genetic disorder of somatic cells, characterized by the accumulation of mutations in genes that regulate cell cycle control, genomic stability, apoptosis, and cellular senescence. These mutations arise through both exogenous and endogenous processes. Exogenous factors include carcinogens from tobacco smoke, radiation, and certain viruses. Endogenous mutations occur due to the inherent chemical instability of DNA, errors during DNA replication, and oxidative damage from normal metabolic processes. A significant proportion of cancer cases are linked to avoidable risk factors such as tobacco use, dietary factors, infections, and exposure to carcinogens. However, spontaneous mutations also play a crucial role. These include depurination and depyrimidation of DNA, errors in DNA proofreading, and deamination of 5-methylcytosine, which can result in C to T base pair substitutions. The accumulation of such mutations, particularly in tumor suppressor genes like p53, can drive carcinogenesis [2].

The complexity of cancer’s onset involves an interplay of genetic predispositions, environmental exposures, and random mutations. For example, the mutational spectra of the p53 gene in various cancers highlight the influence of both endogenous and exogenous mutagenic processes. Understanding these mechanisms is critical for developing targeted cancer therapies, such as stem cell-based treatments that can modulate the tumor microenvironment and exert anti-tumor effects. Cancer affects millions of people globally, with an estimated 19.3 million new cancer cases and 10 million cancer-related deaths in 2020 alone [3].

These figures underscore the substantial impact of cancer on public health and the urgent need for effective treatments. The disease not only poses a significant health burden but also affects the quality of life of patients and their families. Advancements in cancer research and treatment, such as immunotherapy, targeted therapy, and stem cell therapy, continue to evolve, offering hope for better management and potential cures [4].

3 MSCs in Cancer Therapy

3.1 Introduction to MSCs

Mesenchymal stem cells (MSCs) are multipotent stromal cells that possess the remarkable ability to differentiate into multiple specialized cell types, including osteoblasts (bone-forming cells), adipocytes (fat-storing cells), and chondrocytes (cartilage-forming cells). This differentiation potential highlights their critical role in tissue regeneration and repair. MSCs are not limited to a single source; they can be isolated from various human tissues, with bone marrow, adipose tissue, and umbilical cord blood being the most common sources. Each of these sources offers distinct advantages: bone marrow-derived MSCs are traditionally well-studied and are known for their robust differentiation capabilities; adipose tissue provides a more abundant and accessible source; and umbilical cord blood-derived MSCs are valued for their relatively immature state and higher proliferation rates [5]. In addition to their differentiation capabilities, MSCs have garnered significant attention in regenerative medicine due to their anti-inflammatory and immunomodulatory properties. They can modulate immune responses by secreting bioactive molecules that influence the behavior of immune cells, thus reducing inflammation and promoting an environment conducive to healing. This makes them particularly useful in treating inflammatory and autoimmune diseases, where controlling the immune response is crucial.

MSCs influence cancer cells by modulating signaling pathways or affecting pathways of apoptosis and proliferation. They can either promote cancer progression or inhibit cancer depending on the type of MSC and its secretions. However, the dual nature of MSCs’ influence on cancer cells makes them a double-edged sword in cancer therapy. For instance, some studies have demonstrated that MSCs can inhibit tumor growth and reduce metastasis, while others suggest that MSCs might actually support tumor progression by promoting angiogenesis (the formation of new blood vessels) and creating a tumor-friendly microenvironment.

3.2 Therapeutic Advantages of MSCs

MSCs possess a unique ability to migrate to sites of tissue damage, inflammation, and tumors, a process known as homing. This homing ability is driven by the interaction between MSCs and specific chemokines, cytokines, and adhesion molecules that are expressed at the sites of injury or tumors. This characteristic has created promising opportunities in cancer therapy, where MSCs can be engineered to deliver therapeutic agents directly to tumors, thereby increasing the effectiveness of treatments while reducing systemic side effects. The combination of their differentiation potential, immunomodulatory properties, and homing capability makes MSCs a versatile and powerful tool in developing innovative therapeutic strategies for a wide range of medical conditions, including degenerative diseases, immune disorders, and cancer [6].

Building on this, MSCs offer several therapeutic benefits in cancer treatment. Their anti-inflammatory properties play a crucial role in mitigating tumor-induced inflammation, which is often a key factor in cancer progression. Additionally, MSCs have the ability to inhibit cancer cell proliferation and metastasis by secreting bioactive molecules and exosomes. These exosomes, which carry proteins, RNAs, and other molecules, can modulate the tumor microenvironment, thereby influencing cancer progression and the tumor's response to therapy. Furthermore, MSCs can enhance the effects of chemotherapy and radiotherapy by sensitizing cancer cells to these treatments while also supporting the regeneration of normal tissues that have been damaged by these therapies. The combination of their differentiation potential, immunomodulatory properties, homing capability, and ability to interact with the tumor microenvironment makes MSCs a versatile and powerful tool in developing innovative therapeutic strategies for a wide range of medical conditions, including degenerative diseases, immune disorders, and cancer.

For instance, MSC-derived exosomes have been shown to promote chemotherapy resistance in some cancers while enhancing sensitivity in others [7]. This dual role highlights the complexity and potential of MSCs in personalized cancer therapy. Recent studies indicate that MSC-derived exosomes can enhance the sensitivity of cancer cells to chemotherapeutic drugs like paclitaxel and doxorubicin by modulating various signaling pathways and gene expressions. For example, MSCs can transfer miR-122 to hepatocellular carcinoma cells, increasing their sensitivity to chemotherapeutic drugs by downregulating genes associated with drug resistance [8] .This example highlights the sophisticated and context-dependent nature of MSC-based therapies, reinforcing their potential in the future of cancer treatment.

4 HUCMCs in Cancer Therapy

4.1 Introduction to HUCMCs

Human Umbilical Cord Mesenchymal Stem Cells (HUCMCs) are obtained from the umbilical cord, providing a non-invasive and readily accessible source of multipotent stem cells. Like other types of mesenchymal stem cells (MSCs), HUCMCs possess the ability to differentiate into a range of specialized cell types, including osteoblasts, adipocytes, and chondrocytes, and can modulate immune responses, making them valuable for various therapeutic applications [9].

4.2 Mechanisms of HUCMCs in Cancer Therapy

Human Umbilical Cord Mesenchymal Stem Cells (HUCMCs) offer distinct advantages that make them particularly appealing for cancer therapy. They are derived from a non-invasive and abundant source—the umbilical cord—unlike bone marrow or adipose tissue, which require more invasive procedures for collection. HUCMCs exhibit a higher proliferation rate and greater plasticity compared to MSCs from other sources, and they come with a lower risk of ethical concerns and donor variability issues, as the umbilical cord is considered a "waste" product of childbirth [9].

HUCMCs exert their therapeutic effects through several mechanisms. They secrete cytokines and growth factors that promote tissue regeneration and inhibit cancer cell growth. Additionally, HUCMCs can modulate the immune system to enhance the body’s natural anti-tumor responses. Their ability to secrete exosomes containing miRNAs and other regulatory molecules allows them to influence cancer cell behavior and the tumor microenvironment, potentially reversing drug resistance and inhibiting metastasis[7]. This combination of advantageous properties and therapeutic mechanisms underscores the potential of HUCMCs in advancing cancer treatment and regenerative medicine.

For example, HUCMC-derived exosomes have been found to inhibit the epithelial-mesenchymal transition (EMT) in hepatocellular carcinoma cells, enhancing their sensitivity to paclitaxel and other chemotherapeutic agents[8]. Furthermore, HUCMCs can enhance the immune response against tumors by increasing the activity of natural killer (NK) cells and cytotoxic T lymphocytes, providing a multifaceted approach to cancer therapy.

4.3 Other Stem Cell Types in Cancer Therapy

Various other stem cell types have been investigated for their potential in cancer therapy. For instance, adipose-derived mesenchymal stem cells (ADMSCs) have shown promise in delivering chemotherapeutic agents and enhancing their efficacy. The versatility and ease of isolation of these cells make them a convenient option for therapeutic applications..Stem cells from different sources, such as bone marrow and adipose tissue, have different properties and potentials in cancer therapy. ADMSCs, for example, can be easily isolated in large quantities and have shown potential in enhancing drug delivery and reducing side effects. Furthermore, fetal mesenchymal stem cells have been explored for their unique properties, including higher proliferation rates and lower immunogenicity, which might make them more effective in certain therapeutic contexts.

5 Current Limitations and Future Prospects of Stem Cell Therapy

One of the primary challenges of stem cell therapy is immune rejection. The patient's immune system may recognize the transplanted stem cells as foreign and mount an immune response against them, which can lead to the destruction of the transplanted cells and the failure of the therapy. To address this issue, several strategies are employed. Immunosuppressive drugs are commonly used to suppress the patient’s immune response and reduce the risk of rejection. However, these drugs can also increase susceptibility to infections and other complications. An alternative approach is to engineer stem cells to evade immune detection. This can be achieved through genetic modification to express specific surface markers that reduce their recognition by the immune system or by using stem cells derived from the patient's own tissues, thereby minimizing immune incompatibility. Despite these strategies, the risk of immune rejection remains a significant concern and continues to drive research into more effective solutions.

Another critical limitation of stem cell therapy is tumorigenicity, or the potential for stem cells to form tumors. The inherent capacity of stem cells to proliferate and differentiate poses a risk of uncontrolled cell growth, which can lead to tumor formation. This necessitates rigorous screening and genetic modification to ensure the safety of stem cell therapies. For instance, researchers are working on removing or altering genes associated with cancer progression to reduce the risk of tumor development. Advanced techniques, such as CRISPR-Cas9 gene editing, are being utilized to precisely modify the genetic makeup of stem cells to minimize their tumorigenic potential. Additionally, ongoing studies focus on developing robust safety protocols and long-term monitoring to detect and manage any emerging risks associated with stem cell therapies. Addressing the challenge of tumorigenicity is crucial for advancing the clinical application of stem cell therapies and ensuring their safety for patients.

6 Conclusion

This paper examines the potential of stem cells to enhance traditional cancer treatments through their regenerative and differentiation capabilities. Mesenchymal stem cells (MSCs), including those derived from the umbilical cord (HUCMCs), show considerable promise due to their ability to inhibit tumor growth, promote tissue regeneration, and modulate immune responses. Their unique attributes, such as targeted homing to tumor sites and the secretion of bioactive molecules, offer innovative solutions to overcome the limitations of conventional cancer therapies. Despite these promising advancements, several critical challenges must be addressed to fully realize the potential of stem cell therapies. Immune rejection remains a significant concern, as the body may recognize and attack transplanted stem cells. To mitigate this, strategies such as the use of immunosuppressive drugs and genetic engineering to evade immune detection are being explored. Additionally, the risk of tumorigenicity, or the potential for stem cells to form tumors, requires rigorous screening and genetic modifications to ensure safety. Technologies like CRISPR-Cas9 are being investigated to minimize this risk and improve the reliability of stem cell therapies.Future research and technological innovations are anticipated to address these challenges, enhancing the efficacy and safety of stem cell-based treatments.

The limitation of this article is that many of the reviewed studies are either still in the laboratory phase or involve small sample sizes, which constrains the generalizability of the findings. Small sample sizes may not accurately represent the true efficacy and safety of stem cell therapies. Future research should focus on conducting larger-scale clinical trials to confirm the effectiveness and safety of these treatments.