Collection of Wound Exudate From Human Digit Tip Amputations Does Not Impair Regenerative Healing: A Randomized Trial

A Prospective Follow-up Study of Fingertip Amputation Treatment With Semi-occlusive Dressing

Background

The aim of this prospective cohort was to evaluate the conservative treatment of fingertip amputation with exposed bone, with a semi-occlusive dressing.

Methods

Ten patients with an amputation distal to the distal interphalangeal joint were treated via secondary healing under a semi-occlusive film dressing. We followed up the patients weekly until the fingertip had healed, then a final clinical visit at 6 months, and a patient-reported outcome assessment at 2 years after the injury.

Results

All 10 patients completed the 6-month clinical follow-up, and seven patients completed the final patient-rated outcome assessments at 2 years. There were no complications during the study period, all the patients were satisfied with the results, and all answered "fully agree" on choosing the same treatment method again in a similar injury.

Conclusion

Our results show that conservative treatment of fingertip amputation is feasible and can provide good results.

Single-cell transcriptome reveals core cell populations and androgen-RXFP2 axis involved in deer antler full regeneration

Deer antlers constitute a unique mammalian model for the study of both organ formation in postnatal life and annual full regeneration. Previous studies revealed that these events are achieved through the proliferation and differentiation of antlerogenic periosteum (AP) cells and pedicle periosteum (PP) cells, respectively. As the cells resident in the AP and the PP possess stem cell attributes, both antler generation and regeneration are stem cell-based processes. However, the cell composition of each tissue type and molecular events underlying antler development remain poorly characterized. Here, we took the approach of single-cell RNA sequencing (scRNA-Seq) and identified eight cell types (mainly THY1⁺ cells, progenitor cells, and osteochondroblasts) and three core subclusters of the THY1⁺ cells (SC2, SC3, and SC4). Endothelial and mural cells each are heterogeneous at transcriptional level. It was the proliferation of progenitor, mural, and endothelial cells in the activated antler-lineage-specific tissues that drove the rapid formation of the antler. We detected the differences in the initial differentiation process between antler generation and regeneration using pseudotime trajectory analysis. These may be due to the difference in the degree of stemness of the AP-THY1⁺ and PP-THY1⁺ cells. We further found that androgen-RXFP2 axis may be involved in triggering initial antler full regeneration. Fully deciphering the cell composition for these antler tissue types will open up new avenues for elucidating the mechanism underlying antler full renewal in specific and regenerative medicine in general.

Common themes in tetrapod appendage regeneration: a cellular perspective

Complete and perfect regeneration of appendages is a process that has fascinated and perplexed biologists for centuries. Some tetrapods possess amazing regenerative abilities, but the regenerative abilities of others are exceedingly limited. The reasons underlying these differences have largely remained mysterious. A great deal has been learned about the morphological events that accompany successful appendage regeneration, and a handful of experimental manipulations can be reliably applied to block the process. However, only in the last decade has the goal of attaining a thorough molecular and cellular biological understanding of appendage regeneration in tetrapods become within reach. Advances in molecular and genetic tools for interrogating these remarkable events are now allowing for unprecedented access to the fundamental biology at work in appendage regeneration in a variety of species. This information will be critical for integrating the large body of detailed observations from previous centuries with a modern understanding of how cells sense and respond to severe injury and loss of body parts. Understanding commonalities between regenerative modes across diverse species is likely to illuminate the most important aspects of complex tissue regeneration.

Conservative treatment of fingertip injuries in children - first experiences with a novel silicone finger cap that enables woundfluid analysis

Introduction: Human fingertips are able to regenerate soft tissue and skin after amputation injuries with excellent cosmetic and functional results when treated with semiocclusive dressings. Despite bacterial colonizations, proceeding infections are not reported with this management. The underlying mechanisms for this form of regenerative healing as well as for the resilience to infections are not known. Due to the lack of mechanical protection, the leakage of maloderous woundfluid and the sometimes challenging application, conventional film dressings have their problems, especially in treating young children. We therefore treated selected patients with a novel silicone finger cap with an integrated wound fluid reservoir that enables atraumatic routine wound fluid aspiration.

Methods: We report on 34 patients in between 1 and 13 years with traumatic fingertip amputations primarily treated with occlusive dressings. 12 patients were treated with a novel silicone finger cap. We summarized clinical data for each patient. This included photographs and microbiological results from wound fluid analyses, whenever available.

Results: The results of both, conventional film dressing and silicone finger cap treatment, were excellent with no hypersensitivity and no restrictions in sensibility and motility. Even larger pulp defects were rearranged in a round shape and good soft tissue coverage of the distal phalanx was achieved. Nail deformities were not observed. We detected a wide spectrum of both aerobic and anaerobic bacteria in the wound fluids but infections were not observed. Epithelialization times did not differ significantly and no severe complications were seen in all primarily conservatively treated patients.

Conclusion: This study provides preliminary data demonstrating that the treatment with the silicone finger cap leads to excellent clinical results in wound healing. Interestingly, the wounds were colonized with a wide range of bacteria including species that may cause wound infections. However, we saw no proceeding inflammation and the regeneration was undisturbed. In the future, the efficacy of this new management should be evaluated in randomized, controlled clinical trials to confirm the results under standard conditions and get more insight into the role of the wound microbiome as well as other factors that may promote regeneration. The aspirable Reservoir of the finger cap will enable easy atraumatic sampling of wound fluids both for diagnostic and for research purposes as well as possibly allowing direct administration of pro-regenerative drugs in the future.

Study protocol for a randomized controlled pilot-trial on the semiocclusive treatment of fingertip amputation injuries using a novel finger cap

INTRODUCTION

Fingertip amputation injuries are common in all ages. Conservatively treated fingertips can regenerate skin and soft tissues to form a functionally and cosmetically excellent new fingertip. Little is known about this ability that, in humans, is confined to the fingertips. Even less is known about the role of the bacteria that regularly colonize these wounds without negative impact on regeneration and healing.As an alternative to surgery, self-adhesive film dressings are commonly used to establish a wet chamber around the injury. These dressings leak malodorous wound fluid eventually until the wound is dry. Having that into consideration, we have therefore developed a silicone finger cap that forms a mechanically protected, wet chamber around the injury for optimal regeneration conditions. It contains a puncturable reservoir for excess wound fluid, which can be thus routinely analyzed for diagnostic and research purposes.This study protocol explains the first randomized controlled trial (RCT) on the semiocclusive treatment of fingertip amputations in both children and adults comparing traditional film dressings with the novel silicone finger cap. Being the first RCT using 2 medical devices not yet certified for this indication, it will gather valuable information for the understanding of fingertip regeneration and the design of future definitive studies.

METHODS AND ANALYSIS

By employing an innovative pseudo-cross-over-design with a dichotomous primary endpoint based on patients preference, this pilot study will gain statistically significant data with a very limited sample size. Our RCT will investigate acceptance, safety, effectiveness, and efficacy of this novel medical device while gathering information on the clinical course and outcome of conservatively treated fingertip injuries. A total of 22 patients older than 2 years will be randomly assigned to start the conservative treatment with either the traditional film-dressing or the novel finger cap. The treatment will be changed to the other alternative for another 2 weeks before the patient or the guardian is confronted with the decision of which method they would prefer for the rest of the treatment (if required).

ETHICS AND DISSEMINATION

Ethical approval (EK 148042015) of the study protocol has been obtained from Institutional Review Board at the TU Dresden. The trial is registered at the European Database on Medical Devices (EUDAMED-No.: CIV-15-03-013246) and at ClinicalTrials.gov (NCT03089060).

Learning from Mother Nature: Innovative Tools to Boost Endogenous Repair of Critical or Difficult-to-Heal Large Tissue Defects

For repair of chronic or difficult-to-heal tissue lesions and defects, major constraints exist to a broad application of cell therapy and tissue engineering approaches, i.e., transplantation of “ex vivo” expanded autologous stem/progenitor cells, alone or associated with carrier biomaterials. To enable a large number of patients to benefit, new strategies should be considered. One of the main goals of contemporary regenerative medicine is to develop new regenerative therapies, inspired from Mother Nature. In all injured tissues, when platelets are activated by tissue contact, their released factors promote innate immune cell migration to the wound site. Platelet-derived factors and factors secreted by migrating immune cells create an inflammatory microenvironment, in turn, causing the activation of angiogenesis and vasculogenesis processes. Eventually, repair or regeneration of the injured tissue occurs via paracrine signals activating, mobilizing or recruiting to the wound site cells with healing potential, such as stem cells, progenitors, or undifferentiated cells derived from the reprogramming of tissue differentiated cells. This review, largely based on our studies, discusses the identification of new tools, inspired by cellular and molecular mechanisms overseeing physiological tissue healing, that could reactivate dormant endogenous regeneration mechanisms lost during evolution and ontogenesis.