Uncovering the Significance of Tissue Regeneration Enhancer Elements in Mouse Digit Tip Regeneration: A Step Towards Advancing Limb Regrowth.

• Applicant: Dr. Katja Koll
• Subject Area: Orthopaedics, Traumatology, Reconstructive Surgery
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 547486810

When humans lose a limb due to injury, they do not have the natural ability to regrow it. However, certain animals, like fish and salamanders, can regenerate entire limbs. Concentrating on mammalian tissue regeneration, mice show the ability to regrow the tips of their digits following amputation. Given its higher transferability, understanding tissue regeneration in mice is a valuable avenue for developing therapies addressing human limb loss.In this project, the aim is to investigate the process of mouse digit tip regeneration. Within limb regeneration, specific gene sequences known as tissue regeneration enhancer elements (TREEs) play a crucial role in activating or enhancing regeneration. The objective is to identify novel TREEs in mice, which can potentially be utilized for gene therapies in the future. The project entails three steps: Initially, the focus will be on investigating the role of TREEs in the regrowth process. Using a special technique called Massively Parallel Reporter Assays (MPRA) in mice, the objective is to determine the sequences that demonstrate activity during digit regrowth. Furthermore, spatial transcriptomics will be used to identify the active genes in the regrowing fingertip. This comprehensive approach will provide a detailed map of the functionality of these genes across various regions of the fingertip during the regrowth process. Secondly, specialized virus carriers known as adeno-associated virus (AAV) reporter vectors will be developed. In total, four distinct genes that are hypothesized to promote regrowth are each incorporated into an AAV. These genes play roles in cell growth, tissue repair, or the regulation of bone and cartilage development. The intention is to administer these viruses into the mice's bloodstream to genetically modify the injured digit. Through this approach, the contributions of these genes to the digit regeneration process are clarified by analyzing the tissue through microscopic and radiological imaging procedures. Finally, the results of the first two steps will be combined to create 3 to 5 ideal viruses expressing candidate genes that are most promising in enhancing the regrowth of the mice's fingertips. Subsequently, the ideal viruses will be injected into the mice's blood to verify if the gene therapy improves the regrowth of fingertips. The results from this project will help us to understand better which genes play a crucial role during fingertip regrowth in mice. In essence, this research will unlock the secrets behind how mice can regrow their digit tips, intending that these findings could lead to new therapies for humans suffering from limb loss. This project is a step toward understanding and harnessing the natural regenerative abilities observed in mice for the benefit of medical treatments.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: David Brown, Ph.D.