Not all aging cells are bad - some help to heal the body

The idea of removing old, inflammatory cells to extend life has fascinated scientists for years. These cells, called senescent cells, accumulate as we age.

Senescent cells stop dividing, have damaged DNA, and cause inflammation, which is linked to the presence of diseases such as diabetes, dementia, and heart conditions.

While getting rid of aging cells in animals has been shown to extend lifespan, new research shows it’s not always that simple.

Researchers at the University of Connecticut (UConn) recently published a study in Nature Aging that takes a closer look at the role of senescent cells.

They found that not all of these cells are bad – some play helpful roles, like aiding wound healing. This discovery challenges the idea that all senescent cells are harmful and should be eliminated.

What are senescent cells?

These are cells that have stopped dividing and are no longer functioning like normal, healthy cells. They accumulate in the body as we age and are often linked to various age-related diseases.

While they cause inflammation and can contribute to disease, some senescent cells actually have useful roles. For instance, they can help with tissue repair and regeneration in some cases.

“Senescent cells are not homogenous. They have different characteristics and functions, and might be very different in many ways,” explained Ming Xu, an assistant professor at the UConn Center on Aging and the Department of Genetics & Genome Sciences.

Two types of senescent cells

Ming Xu and his team – including Ph.D. student Nathan Gasek, graduate student Junyu Zhu, and postdoctoral researcher Pengyi Yan – focused on two types of senescent cells.

These groups are identified based on the presence of two genes: p16 and p21. Earlier studies have shown that removing either type can make mice live longer. But their roles in the body vary a lot.

The team wanted to learn more about p21 cells, especially their role in wound healing. By removing p21 cells from young mice with skin wounds, they found something surprising.

The wounds healed about 25% faster in female mice, but the effect wasn’t seen in males. This finding is the opposite of what happens with p16 cells, which earlier research showed also help with wound healing.

Interestingly, p21 cells are often found in connective tissue, skin, and immune cells. They have a unique pro-inflammatory profile that sets them apart from p16 cells. This highlights the complexity of senescent cells and why a one-size-fits-all approach to dealing with them represents an oversimplification.

Significance of the research

This research has big implications for anti-aging therapies. Instead of simply trying to eliminate all senescent cells, scientists can now focus on targeting the harmful ones while keeping the helpful ones.

This could lead to better treatments for aging-related issues and faster wound healing.

“The investigators hope their study can bring attention to others in the field about the diversity of cellular senescence and the importance of thoroughly evaluating the roles of various senescent cell populations across a broad spectrum of conditions,” noted the researchers.

Developing drugs to target aging cells

The UConn team plans to dig deeper into how p21 cells affect wound healing in conditions like diabetes and advanced aging.

They also want to develop drugs that can specifically target different types of senescent cells. This could revolutionize how we treat aging and related diseases.

This study reminds us that senescent cells aren’t all bad. They’re more like a mixed bag – some harm us, while others help us heal.

By understanding their diversity, scientists can create smarter, more precise treatments that improve health and extend life without unwanted side effects.

Additional roles of senescent cells

While the study focused on the role of senescent cells in aging and wound healing, these cells have other crucial functions that are important for the body.

Beyond just causing inflammation, senescent cells can play key roles in maintaining tissue integrity and regulating certain processes in the body.

Tissue regeneration

Senescent cells contribute to the regeneration of tissues after injury. They help by secreting factors that promote the healing of damaged areas, which is crucial for proper tissue repair. In some cases, these cells can help prevent further tissue degeneration.

Immune system modulation

Some types of senescent cells can influence the immune system by producing signals that either activate or suppress immune responses.

This can be important for controlling infections or regulating chronic inflammation in the body, especially as we age.

Cancer suppression

In certain situations, senescent cells may help suppress the growth of cancer cells by preventing damaged cells from dividing.

This process, known as “cellular senescence,” can act as a protective mechanism against the development of tumors, although its role is complex and context-dependent.

Stem cell regulation

Senescent cells can also interact with stem cells, which are responsible for generating new cells in the body.

They can help maintain the balance between the activation of stem cells and their dormancy, ensuring proper regeneration and preventing overgrowth, which can lead to cancer.

Understanding these additional functions of senescent cells highlights the importance of maintaining a balance in how we approach treatments aimed at targeting these cells.

The study is published in the journal Nature Aging.

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