Stem cells are essential in tissue regeneration and repair. Found throughout the body, stem cells serve as first responders in responding to damaged areas by healing themselves quickly – though their impressive regeneration abilities begin diminishing as we age.
Lower animals possess remarkable regeneration capabilities; for example, Planaria can regrow its entire body in five days and salamanders their lost heads in 7-10. Humans too could potentially extend their lifespan with stem cell therapy.
What are Stem Cells?
Stem cells are unique cells found throughout the body that can give rise to various types of specialized cells, including those in blood, brain, bone, muscle and liver tissues. Stem cells play an integral part in maintaining organ health as well as healing after injury has taken place.
Stem cell research is an integral aspect of medical science and holds great promise for new treatments and cures. However, there are still many unknowns surrounding stem cells and how they operate; there may also be ethical concerns relating to their use; thus making better regulation more essential than ever for using these cells effectively.
Aging can lead to the gradual loss of function of tissue-resident adult stem cells, due to factors like DNA damage accumulation, insufficient protein homeostasis and altered communication channels, stem cell exhaustion or physical exercise calorie restriction epigenetic reprogramming and altered concentrations of circulating blood factors. New studies show several strategies may rejuvenate aged TRCs – physical exercise calorie restriction epigenetic reprogramming changes concentration of circulating blood factors can help rejuvenate TRCs
Hematopoietic stem cells (HSCs), found most frequently in bone marrow, are responsible for creating all the various blood cells present within our bodies. Other stem cell sources can also be found throughout tissue such as skeletal muscles, brain, liver or skin.
One of the primary functions of HSCs is providing mature cells to replenish damaged or lost ones in blood, muscle, bone and brain tissues. Their unique capacity for producing many specialized cell types makes stem cells vital in maintaining integrity and proper functioning throughout our bodies’ tissues.
As stem cells divide, their telomeres become gradually shorter. When this becomes too short, telomeres trigger a program of cellular senescence that eventually results in cell death. For HSCs aging over time, accumulation of DNA damage, altered protein homeostasis, and decreased expression of redox pathways all contribute to senescence progression and eventually its inevitable death.
Why are Stem Cells so Important?
Stem cells hold out much promise as potential replacement parts for diseased or damaged tissues, such as skin, muscle and heart tissue. Researchers are working hard to use stem cells as replacement insulin-producing beta cells in diabetes treatments as well as make new heart muscle cells using stem cells; stem cells also play an invaluable role in clinical trial medication testing before giving them to people taking part.
Stem cell research’s ultimate objective is to reverse or slow aging. Many age-related conditions, including cancer, Alzheimer’s, Parkinson’s, heart disease and debilitating strokes are related to cells losing their essential functions as people age; animal models have demonstrated how stem cells can rejuvenate older cells for improved health and extended longevity.
Stem cells are essential to life as they provide the only means of replenishing cells that have become worn down from regular use, injury or disease. Stem cells play an integral part in creating new organs; in embryonic development they produce all the specialized cells required for development; while adults make use of discrete populations of adult stem cells to replenish tissues like bone marrow, blood and muscle by replenishing specialized cells to keep populations stable.
As these cells age, their telomeres shorten with each round of cell division until their division stops and they eventually die off or stop reproducing altogether. A DNA repair process known as telomerase helps counter this shortening and maintain healthy stem cells; unfortunately however, its activity decreases with increasing age which has been linked with both cell aging and disease[2, 28].
Researchers have recently discovered that inducing expression of Yamanaka factors can revitalize adult stem cells, turning them into induced pluripotent stem (iPS) cells that can then be directed into any cell in the body – including neurons to replace damaged neurons in the brain or spinal cord.
Scientists have noted that injecting iPS cells directly into older mice’s bloodstream has the power to restore organs by replacing old, specialized cells with fresh ones from younger mice. Richard Lee of Forst Family Professor of Stem Cell and Regenerative Biology attached the circulatory systems of young and old mice so that blood from one stayed within its system – leading to improvement in muscle tone and heart function for both.
How do Stem Cells Reverse Aging?
Stem cells have the power to replace damaged cells and differentiate into many cell types, yet with age comes their ability to do so decreasing. Scientists are working hard to understand what causes this decline and reverse it; one solution may lie within stem cell function genes like NANOG; two studies from Andreadis’ lab recently took key steps toward this end: one, published Feb 16 in Cell Reports, investigated how NANOG could restore mitochondrial function while increasing longevity in skeletal muscle stem cells while extending lifespan by NANOG use.
Researchers are exploring how stem cells collaborate to perform their regenerative roles. Their aim is to discover which signals stem cells use to communicate between each other, solicit help from neighboring cells, and judge whether or not their task warrants further effort. It’s believed that one signaling pathway responsible for driving stem cell responses to stimuli for regeneration involves cytokines and growth factors which serve as “communicative language” within our bodies during times of injury or illness, released during times of strain on healing processes.
Additionally, scientists are working on strategies to extend the longevity of existing stem cells while returning them back to their pluripotency state. Reprogramming factors are being introduced into differentiated cells to alter their expression patterns so as to resemble those seen in pluripotent cells; this process may take several weeks and involves forcing expression of several genes known as master regulators of pluripotency.
An effective strategy for prolonging the lifespan of existing stem cells is clearing away senescent cells – those cells which have stopped dividing but remain present in tissues and organs after no longer dividing – that have begun accumulating, blocking the proliferation of new cells and leading to inflammation. Mice treated with dasatinib or quercetin for their antisenescence properties had longer median lifespans compared with untreated animals, suggesting that reverse senescence in existing stem cells can help dramatically enhance health and longevity benefits in humans alike.
How can Stem Cells Reverse Aging?
Science’s belief that aging can be reversed has inspired scientists to pursue ways of stopping functional decline and restoring regeneration capacity in cells and tissues. University of Buffalo chemical engineer Stelios Andreadis discovered that forcing expression of an embryonic gene called NANOG on aged adult stem cells and skeletal muscle cells reprograms them back into more youthful, fully functional versions of themselves – this could provide potential therapies that increase quality of life for those suffering from age-related diseases like heart failure, rheumatoid arthritis, diabetes or cancer patients.
One of the primary causes of cell senescence and eventual death is shortening of telomeres, protective structures which guard DNA against degradation. Telomeres become shorter with every cell division until eventually they get too short, stopping cell division altogether and eventually leading to death. Telomerase is known to keep telomeres from shortening, though its activity diminishes with age; one study with mice demonstrated how reactivating it by injecting human iPSCs back into them reversed aging effects while restoring normal stem cell function – something telomerase cannot do.
Scientists are exploring what factors cause stem cells to differentiate into specialized cells, by studying the complex network of stimulating signals received from surrounding cells and environments. Stem cells respond to signals emanating from injured or diseased tissues containing cytokines and growth factors; these signals tell stem cells where to go, what they need to do there and whether or not their presence is necessary or needed.
Stem cell therapy is currently under clinical development to treat various conditions associated with aging, including physical frailty in older people and facial skin aging. Furthermore, mesenchymal stem cells are being evaluated as an adjunct therapy for reversing some signs of aging in a mouse model of Alzheimer’s disease. More research will be required before any applications of stem cell therapy translate directly to humans; nonetheless evidence has already begun emerging supporting them as viable options.
