Overview and Background

• This research paper introduces the BioDome Regenerative Sleeve, a device designed to stimulate tissue regeneration in a mouse’s amputated digit.
• The goal is to create a controlled, moist environment that uses both biochemical agents and electrical (biophysical) stimulation to promote regrowth.
• It combines a chemical treatment (porcine urinary bladder matrix pepsin digest) with low-level electrical stimulation to mimic the natural signals that encourage regeneration.

What is the BioDome and Its Purpose?

• The BioDome is a multi-component sleeve that fits over the wound at an amputated digit.
• It is engineered to keep the wound hydrated and protected, similar to creating an in utero environment for healing.
• It uses a combination of:
  • Biochemical stimulation (delivering a regenerative cocktail), and
  • Biophysical stimulation (providing a controlled electrical current)
• Purpose: To kick-start the tissue regeneration process, reduce scarring, and promote the regrowth of lost structures.

Step-by-Step Device Design and Operation

• Device Components:
  • Polyimide cuff – a small inner sleeve that contacts the digit.
  • Silicone septum and retaining band – creates a seal and allows injection of treatments.
  • Nylon reservoir – holds the liquid treatment (about 30 uL capacity).
  • Stainless steel cathode – integrated to deliver electrical stimulation.
  • Temporary implantable stainless steel anode – used externally to complete the electrical circuit.
• Assembly:
  • All components are aligned and secured with a medical-grade epoxy.
  • The device is sterilized with ethylene oxide gas and then vented before use.
• Application:
  • During surgery, the BioDome is affixed to the amputated digit using a tissue adhesive (VetBond) to ensure a watertight seal.
  • This seal prevents dehydration and keeps the wound in a controlled environment.
• Electrical Stimulation:
  • An external power source delivers a small current (6.4 microamperes) for 15 minutes on days 0, 1, and 3.
  • The current flows from the temporary anode to the built-in cathode, mimicking natural bioelectric signals.
• Pharmacological Treatment:
  • A regenerative cocktail (UBM pepsin digest) is injected into the nylon reservoir using hypodermic syringes.
  • The injection is done carefully to avoid air bubbles, ensuring a continuous liquid environment.

Animal Study Methodology

• Subjects: C57BL/6 mice, 6–8 weeks old, weighing around 20–25 grams.
• Preparation:
  • Mice are anesthetized with ketamine and xylazine.
  • The surgical area (right hind foot) is cleaned and prepped using ethanol and povidone iodine.
• Surgical Procedure:
  • A digit (the middle finger of the right hind foot) is amputated using fine bone scissors under a microscope.
  • The BioDome device is then installed on the amputated digit.
• Treatment Groups:
  • Group 1: Received a BioDome with a neutralized pepsin buffer (control) plus electrical stimulation.
  • Group 2: Received a BioDome with the UBM pepsin digest treatment plus electrical stimulation.
  • Additional controls include mice with no treatment and mice with a BioDome but no electrical stimulation.
• Post-Operative Care:
  • Mice recover on a heating pad and are given buprenorphine to manage pain.
  • They are monitored until they regain movement and then housed individually.
  • On day 14, mice are euthanized for tissue collection and histological analysis.

Results and Observations

• Device Performance:
  • The BioDome remained attached for up to 6 days, maintaining a moist, controlled environment.
  • Minimal irritation was observed once the animals acclimated.
• Histology Findings (Day 14):
  • Untreated Digits: Showed a thin wound epithelium with scar tissue and minimal gland formation.
  • BioDome Only with Electrical Stimulation: Displayed a thicker wound epithelium and some new gland development.
  • UBM Pepsin Digest Control + Electrical Stimulation: Exhibited increased collagen deposition, thicker epithelia, and organized clusters of large mononuclear eosinophilic cells (LMECs), which are key regenerative cells.
  • UBM Pepsin Digest Treatment + Electrical Stimulation: Showed the most advanced regeneration, with pronounced gland formation, vascularization, and clear signs of bone remodeling.
• Key Observations:
  • The combination of electrical stimulation and biochemical treatment significantly enhanced tissue regeneration compared to controls.
  • Regenerative signs include increased cell proliferation, organized collagen networks, and new tissue structures.

Discussion and Implications

• The BioDome creates a protected, moist microenvironment that is crucial for tissue repair, much like keeping a plant watered to encourage growth.
• Electrical stimulation provides bioelectric cues that guide cells to migrate and proliferate, similar to how a gentle current can steer a boat.
• Challenges noted include:
  • A short adhesion time (up to 6 days) to avoid irritation or necrosis.
  • A small reservoir volume that may limit treatment delivery.
• Future improvements could involve redesigning the cuff for a better fit and increasing the reservoir capacity for longer treatments.
• This approach holds promise for advancing regenerative medicine, especially in treating limb loss and severe injuries.

Conclusions

• A controlled, well-hydrated wound environment combined with targeted electrical and biochemical stimulation can significantly enhance tissue regeneration.
• The BioDome device shows potential as a research tool for understanding and promoting regeneration.
• While the preliminary results are promising, further design modifications and longer-term studies are needed before considering clinical applications.

观察与背景简介

• 本研究介绍了一种名为 BioDome 再生袖套的装置，旨在刺激小鼠截肢指端的组织再生。
• 目标是创造一个受控且湿润的环境，利用生化物质和电生理（生物物理）刺激来促进组织再生。
• 该装置结合了化学治疗（使用猪尿膀胱基质胰蛋白消化液）和低强度电刺激，模拟自然再生信号。

BioDome 的目的与作用

• BioDome 是一个多组件袖套，可覆盖在截肢指端的伤口上。
• 它设计用来保持伤口湿润和保护伤口，类似于为植物提供充足的水分以促进生长的环境。
• 其主要作用是结合以下两种刺激方式：
  • 生化刺激（注入再生性混合液），以及
  • 生物物理刺激（提供受控的电流）
• 目的：启动组织再生过程，减少疤痕形成，并促进失去结构的再长。

设备设计与操作步骤

• 设备组件：
  • 聚酰亚胺袖套 – 与指端直接接触的小型内衬。
  • 硅胶隔膜及固定带 – 用于形成密封，并允许注射治疗液。
  • 尼龙储液器 – 储存液体治疗剂（容量约 30 微升）。
  • 不锈钢阴极 – 集成于装置内，用于传递电刺激。
  • 临时植入的不锈钢阳极 – 外部使用以完成电路。
• 组装：
  • 各组件使用医用环氧胶对齐并固定。
  • 装置经过环氧乙烯气体灭菌处理，并在使用前进行通风。
• 应用：
  • 手术中，使用组织黏合剂（VetBond）将 BioDome 固定在截肢指端，确保形成水密封。
  • 这种密封防止伤口脱水，并维持一个受控环境。
• 电刺激：
  • 外部电源在第 0、1 和 3 天以 6.4 微安电流刺激 15 分钟。
  • 电流从临时阳极流向内置阴极，模拟自然的生物电信号。
• 药物治疗：
  • 利用注射器将含有再生混合液（UBM 胰蛋白消化液）的治疗液注入尼龙储液器中。
  • 注射过程中需小心排除气泡，确保液体环境的连续性。

动物实验方法

• 实验对象：使用 C57BL/6 小鼠，6-8 周龄，体重约 20-25 克。
• 准备工作：
  • 通过注射酮胺和盐酸赛拉嗪使小鼠麻醉。
  • 用 70% 酒精和 10% 含碘消毒液清洁右后足的手术区域。
• 手术过程：
  • 在显微镜下，使用精细骨剪在右后足中间指的第二指节处进行截肢。
  • 随后将 BioDome 装置安装在截肢指端上。
• 分组：
  • 第一组：使用含中性胰蛋白缓冲液（对照）的 BioDome 并给予电刺激。
  • 第二组：使用含 UBM 胰蛋白消化液的 BioDome 并给予电刺激。
  • 另外设有未处理组以及仅装置 BioDome 但无电刺激的对照组。
• 术后护理：
  • 小鼠在加热垫上恢复，并给予布洛芬样镇痛剂缓解疼痛。
  • 待小鼠恢复自主活动后，单独饲养。
  • 第 14 天处死后取样进行组织学分析。

结果与观察

• 装置表现：
  • BioDome 可在截肢后持续附着达 6 天，维持伤口湿润和受控的环境。
  • 动物适应后，仅有轻微啃咬或抓挠现象。
• 组织学发现（第 14 天）：
  • 未处理组：显示出薄的伤口上皮、疤痕组织及极少的新腺体形成。
  • 仅用 BioDome 加电刺激组：上皮增厚，部分新腺体出现。
  • 对照 UBM 胰蛋白消化液组 + 电刺激：观察到胶原沉积增加，上皮明显增厚，并见到大单核嗜酸性细胞（LMEC）呈现一定的组织结构。
  • UBM 胰蛋白消化液处理组 + 电刺激：再生最为明显，表现为新腺体、血管生成及骨重塑迹象明显。
• 关键观察：
  • 电刺激与生化治疗联合使用显著提高了组织再生效果，相较于对照组有更好的细胞增生和组织结构重建。

讨论与启示

• BioDome 创造了一个保护性湿润的微环境，对促进伤口修复至关重要，就像植物需要充足的水分才能茁壮生长。
• 电刺激为细胞提供了类似自然的生物电信号，指引细胞迁移和增殖，类似于缓流能引导小船前行。
• 存在的问题包括：
  • 装置的附着时间较短（约 6 天），以避免引起过度刺激或组织坏死；
  • 储液器容量较小，可能限制治疗液的持续供应。
• 未来的改进可考虑设计更灵活、扩展容量的 cuff，以延长治疗时间并减少刺激。
• 这种方法为未来治疗四肢缺失和严重创伤提供了新的研究方向和可能的临床应用前景。

结论

• 研究表明，保持伤口湿润的环境结合定向的电刺激与生化治疗，可显著促进组织再生。
• BioDome 装置作为研究工具显示出其在调控再生过程中的潜力。
• 尽管初步结果令人鼓舞，但仍需进一步改进设计和开展长期研究，才能向临床应用迈进。