Regenerative medicine

For centuries, scientists have been captivated by the phenomenal feats of regeneration found in nature. Despite decades of research, attempts to replace or repair parts of the human body have met with only modest success. Fresh understanding of organ formation coupled with new technologies may help to unlock long-sought cures.

Stem-cell therapy promises to restore motor function after a stroke or spinal-cord injury, but neurologists are proceeding with caution.

Advances in technology have outpaced our understanding of organ development and injury response. It's time to reassess, says Stephen Badylak.

Machines that deposit cell-laden inks are constructing tissues and organs, one layer at a time.

Some animals can regrow body parts with ease. Biologists hope to figure out their secrets and apply them to humans.

Cell therapy could cure type 1 diabetes — if only the immune system didn't get in the way.

Adult stem cells have become a regulatory battleground as clinicians, scientists and ethicists debate whether the road to the clinic should be shorter.

The regenerative properties of muscle stem cells decline with age as the stem cells enter an irreversible state of senescence; a study of mouse muscle stem cells reveals that entry into senescence is an autophagy-dependent process and promoting autophagy in old satellite cells can reverse senescence and restore their regenerative properties in an injury model.

An injury-dependent enhancer element is identified that activates gene expression in regenerating zebrafish tissues and can be engineered into DNA constructs that increase tissue regenerative capacity; the element is also active in injured mouse tissue.

Grafting of caudalized rodent or human neural progenitor cells into sites of spinal cord injury enables true regeneration of damaged corticospinal axons in rodents. Regenerating axons form functional synapses within the graft, can extend beyond the lesion site, and help to support functional motor recovery.

Resection of the diseased gastrointestinal tract can lead to surgical complications and low quality of life. In this Review, Bitar summarizes advances in gastrointestinal tissue engineering and regenerative medicine that aim to overcome these complications and restore tissue function.

The clinical translation of biomaterials for tissue engineering reveals their therapeutic performance and relevance, and thus enables the improvement of biomaterials design. In this Review, the design and translation of biomaterials, particularly cartilage and cornea repair, and a new understanding of the interaction between biomaterials and the host immune system are discussed.

The long-standing puzzle of why salamander limb regeneration requires anterior and posterior tissue interaction has been solved by the demonstration that fibroblast growth factor 8 and sonic hedgehog are key anterior and posterior cross-inductive signals that drive regeneration.

Strategies for inducing immunological tolerance to transplanted cells are an important component of regenerative therapies.

In this Perspective, the authors discuss the importance of intrinsic and extrinsic factors in muscle regeneration, and they conclude that both are necessary for the action of muscle stem cells in the aging process.

Sustained delivery of axon-specific growth factors not typically present in spinal cord lesions allows for robust axonal regrowth only if the astrocytic scar is present—a result that questions the prevailing dogma and suggests that astrocytic scarring aids rather than prevents central nervous system axon regeneration post injury.