Translating Periosteum's Regenerative Power: Insights From Quantitative Analysis of Tissue Genesis With a Periosteum Substitute Implant.

: An abundance of surgical studies during the past 2 centuries provide empirical evidence of periosteum's regenerative power for reconstructing tissues as diverse as trachea and bone. This study aimed to develop quantitative, efficacy-based measures, thereby providing translational guidelines for the use of periosteum to harness the body's own healing potential and generate target tissues. The current study quantitatively and qualitatively demonstrated tissue generation modulated by a periosteum substitute membrane that replicates the structural constituents of native periosteum (elastin, collagen, progenitor cells) and its barrier, extracellular, and cellular properties. It shows the potentiation of the periosteum's regenerative capacity through the progenitor cells that inhabit the tissue, biological factors intrinsic to the extracellular matrix of periosteum, and mechanobiological factors related to implant design and implementation. In contrast to the direct intramembranous bone generated in defects surrounded by patent periosteum in situ, tissue generation in bone defects bounded by the periosteum substitute implant occurred primarily via endochondral mechanisms whereby cartilage was first generated and then converted to bone. In addition, in defects treated with the periosteum substitute, tissue generation was highest along the major centroidal axis, which is most resistant to prevailing bending loads. Taken together, these data indicate the possibility of designing modular periosteum substitute implants that can be tuned for vectorial and spatiotemporal delivery of biological agents and facilitation of target tissue genesis for diverse surgical scenarios and regenerative medicine approaches. It also underscores the potential to develop physical therapy protocols to maximize tissue genesis via the implant's mechanoactive properties. SIGNIFICANCE: In the past 2 centuries, the periosteum, a niche for stem cells and super-smart biological material, has been used empirically in surgery to repair tissues as diverse as trachea and bone. In the past 25 years, the number of articles indexed in PubMed for the keywords "periosteum and tissue engineering" and "periosteum and regenerative medicine" has burgeoned. Yet the biggest limitation to the prescriptive use of periosteum is lack of easy access, giving impetus to the development of periosteum substitutes. Recent studies have opened up the possibility to bank periosteal tissues (e.g., from the femoral neck during routine resection for implantation of hip replacements). This study used an interdisciplinary, quantitative approach to assess tissue genesis in modular periosteum substitute implants, with the aim to provide translational strategies for regenerative medicine and tissue engineering.