Peripheral nerve injury is a common disabling clinical disease. Compared with the central nervous system, peripheral nerve structure is simpler and easier to regenerate, and with the development of microsurgical equipment and techniques, the clinical treatment of peripheral nerve injury has been improving. For short defect gaps, direct fine suture or small gap cannula repair is possible; for longer defect distances, nerve tissue grafting or nerve conduit bridging is required. Due to the shortage of autologous nerve graft donors and the limitations of current clinical nerve conduits, the treatment of long, thick nerve defects and multiple nerve injuries remains challenging because of the demanding conditions that need to be provided to allow better nerve regeneration. Nerve regeneration requires a “single compartment” It has long been recognized that nerve regeneration requires its own “single compartment”, a separate section of nerve conduit that provides space for nerve regeneration and avoids the invasion of surrounding scar tissue. The question, however, is what to do with this “single compartment” and how to do it. The nerve conduit, also known as the nerve regeneration chamber, is the vehicle used to repair the nerve defect. Finding, inventing, and combining various tissue materials that can be used for repair to prepare bioactive catheters and build tissue-engineered nerves has been a hot topic of research in recent years. In the early days, various catheter materials were tried, ranging from arterial and venous to silicone materials, but their application revealed that they either could not adjust the diameter of the catheter according to the thickness of the nerve or were left in the patient for a long time, compressing the nerve and requiring reoperation to remove the catheter. Today, tissue-engineered nerves offer new hope for improving the repair of long segments and thick peripheral nerve defects. Based on the experience of others, we chose chitosan to make a biodegradable polymer catheter. Chitosan, which can be degraded to monosaccharides in vivo, is a good repair material with essentially non-toxic effects on nerve cells. In recent years, there have been many reports on the application of chitosan nerve catheters for repairing nerve injuries, and the research direction has gradually evolved from the early use of single material catheters for repairing nerve defects to the use of composite catheters. As for absorbability, it should be said that this is a very interesting research direction. Current studies show that peripheral nerve growth in experimental animals, goats, takes approximately one to one and a half years, during which time the structure of the nerve conduit needs to be maintained long enough to allow the formation of a fibrin matrix to connect the proximal and distal nerve stumps of the defective nerve. Once the initial fibrin matrix is formed, the nerve scaffold should degrade within a reasonable amount of time. Otherwise, nerve regeneration may be delayed, collapsing and compressing the lumen of the duct, causing fibrosis of the outer layer of the nerve, thus preventing nerve regeneration and maturation. Nerve regeneration requires “external forces” The ideal catheter is not the only condition that can help nerve repair. It is now believed that to increase the length, diameter, and rate of regeneration of repaired nerves, new biologically active catheters need to be actively explored, for example, in combination with various types of seed cells to form tissue-engineered artificial nerves. Bone marrow mononuclear cells have a high degree of self-renewal ability and can replicate themselves under certain conditions; they also have a multidirectional differentiation potential and can differentiate into a variety of cells. For nerve repair, the greatest advantage of these cells is that they can facilitate autologous transplantation, secrete various cytokines and trophic factors, promote axonal remyelination, and inhibit neuronal apoptosis. Thus, bone marrow single nucleus cells have long been used for peripheral nerve defect repair experiments in animal models such as rats, rabbits, dogs and monkeys, and many results have been obtained. However, the commonly used experimental animals (including monkeys, whose nerves are also much finer than those of humans) are very different from humans, especially because many experiments are performed in small animals, and the process of obtaining autologous bone marrow SNCCs can cause the death of the animals, so it is difficult to speculate what kind of effect it has on nerve regeneration. We therefore attempted to use a large mammal, the goat, to harvest its own bone marrow in the hope of improving the clinical translation of the study. Fortunately, after a series of studies, we finally confirmed that the chitosan catheter + autologous bone marrow single nucleated cells, constructed as a tissue-engineered artificial nerve, could repair a 30 mm defect of the common peroneal nerve in goats with similar results as autologous nerve grafts: the animal’s behavior improved close to normal; the conduction velocity of the regenerated nerve was not significantly different from that of the autologous nerve graft group; the diameter of the new nerve fibers was thinner than normal; and the myelin sheath was thinner than normal. The myelin sheath was thinner and more dense than normal, but the regenerated axons penetrated the full length of the bridges. In contrast, no significant regenerative repair of nerves was seen in the saline control group, which was significantly different compared with the bone marrow single nucleus cell group and the autologous nerve graft group.