**2. Preparation of placental extract**

membranes, umbilical cord, amniotic fluid, placental extracts, and cord blood stem cells. Methods of application widely vary from subcutaneous, intramuscular, intravenous, intraop-

Research on human placental extract began to thrive from the description on the method of its preparation by Russian ophthalmologist Filatov [4]. Filatov initially observed that grafting-preserved human corneas had better clinical outcomes than freshly isolated ones. He convinced that isolated tissues readjusted themselves to develop biogenic stimulators under unfavorable environmental factors. He advocated the principle of therapeutic tissues which could exhibit curative effects by adapting themselves to the tissues affected by the pathological process. Since placenta is a storehouse of potent biogenic stimulators, the application of placental extract ranges from immunology, stem cell research, genetics, and cancer research to tissue engineering. Placental extracts were demonstrated to contain wide range of peptides,

proteins, minerals, amino acids, nucleotides, carbohydrates, and steroid hormones.

arthritic knee joints in rats [13].

114 Placenta

treatment of respective pain syndromes is also explored.

Experimental evidence has accumulated on the therapeutic effects of placental extracts. One of the most important roles of the placenta is to protect the embryos from oxidative stress, and therefore, placental extract has antioxidative properties [5]. Antioxidant properties of placental extract are usually associated with the protein components, especially alpha-fetoprotein [6]. Injecting placental extract to a wound margin [7] or applying placental extract topically to chronic nonhealing wounds [8] promoted healing of injured tissues. This mechanism appears to be related to an increase in transforming growth factor-beta (TGF-β) in the early phase of wound healing and vascular endothelial growth factor (VEGF) in the late phase [8]. The regeneration of sciatic axons by placental extract injection was validated by increased synthesis of regeneration-related protein factors such as GAP-43 and Cdc2 [9]. Application of placental extract in menopausal disorders allowed reducing the number of hot flushes and normalized hormone profiles [10]. Experimental animal model studies showed that placental extract decreased symptoms of fatigue and increased resistance to physical stress [11]. Placental extracts were also demonstrated to have anti-inflammatory effects in both animals and humans. In adjuvant-induced polyarthritic rats, injection of placental extract was demonstrated to alleviate arthritic symptoms including joint destruction and expression profiles of inflammatory cytokines [12]. Intra-articular injection of placental extract reduced deformity of knee joints and inhibited matrix metalloproteinase-2 and -9 activities of cartilages of osteo-

Recently, acupuncture point injection (API), an injection at an acupuncture point of a small amount of medicinal solution, has been widely used for the treatment of various pain syndromes in China and Korea. API is derived from intramuscular injection in Western medicine and then gradually integrated into traditional Chinese medicine [14]. The medical agents administered in acupuncture points are thought to play a synergistic effect with acupuncture point stimulation, and this method is believed to have a more sustained effect than the traditional acupuncture needling or simple intramuscular injection [15]. API is reported to increase cerebral blood flow, improve adjuvant arthritis, and have analgesic and anticoagulatory effects [16–18]. In clinical studies, API improved cervical disc herniation, knee osteoarthritis, and low back pain [19–21]. Here, we intended to propose an API with placental extract in treating chronic pain syndromes. The mechanistic explanation of acupuncture points employed in the

erative, biocovers, and substitutive material to oral administration [1–3].

Placental extracts are classified to several types depending on the methods of its preparation. Initial extraction was done by employing the Filatov's procedure [4] but an acid-hydrolyzed water extraction is prevailing in Korea due to its high recovery of functional macromolecules from placental tissues. Human placentas, collected upon full-term delivery, were tested for human immunodeficiency virus and hepatitis B and C viruses. They were cut into pieces, defatted with acetone, and extracted with water through pepsin and hydrochloric acidcatalyzed hydrolysis. Resulting placental extract was tested for germ-free, antihistamine, and endotoxin-free under the regulation of Korean Food and Drug Administration. The final placental extract product was sterilized, packaged at 2 ml/ampule, and approved for injection for human by subcutaneous and intramuscular. Insoluble macromolecules, such as polysaccharide, polynucleotide, etc., were excluded during the manufacturing processes. The trade name of the extract, "Laennec", is provided from Green Cross Ltd. (Yongin, Korea). Kong et al. [22] analyzed and reported the levels of cytokines and hormones of Laennec by using automated biochip array technology.
